2020 Chevrolet Silverado & GMC Sierra 2500HD-3500HD New Model Features

SEOCONTENT-START

Service Bulletin Bulletin No.: 19-NA-091
Date: June, 2019
INFORMATION
Subject: 2020 Chevrolet Silverado and GMC Sierra 2500HD-3500HD New Model Features
Brand: Model:
Model Year: VIN:
Engine: Transmission:
From: To: From: To:
Chevrolet
GMC
Silverado
2500HD-
3500HD
Sierra
2500HD-
3500HD
2020 —
6.6L, V8, SIDI,
VVT, Cast Iron,
Gasoline —
RPO L8T
Duramax® 6.6L
V8, DI,
Turbocharged
Diesel, GEN 5,
VAR. 1 —
RPO L5P
6-Speed
Automatic
6L90, HMD, —
RPO MYD
Allison® 10-
Speed
Automatic
10L1000, GRX,
GEN 1, VAR 1
— RPO MGM
OR
Allison® 10-
Speed
Automatic
10L1000, GRX,
GEN 2, VAR 2
with PTO—
RPO MGU
Involved Countries and Regions North America, South America, Israel and Middle East
Overview
Bulletin Purpose
This purpose of this bulletin is to introduce the
completely new 2020 Chevrolet Silverado and GMC
Sierra 2500HD-3500HD pickup trucks. This bulletin will
help the Service Department Personnel become
familiar with the all-new 6.6L V8 — RPO L8T gasoline
engine equipped with the 6-speed 6L90 automatic
transmission, and the Duramax® 6.6L V8 — RPO L5P
diesel engine equipped with the all-new Allison®
Branded – General Motors manufactured 10-speed
automatic transmission with an available integrated
PTO option, the brake system, SIR system, and other
general information for these vehicles.
Available in ¾-ton 2500, 1-ton 3500 single rear wheel,
and 1-ton 3500 dual rear wheel configurations with
2WD or 4WD. These trucks have at least 10 inches
(25.4 cm) of ground clearance, with an improved
approach angle, and a repositioned diesel exhaust fluid
(DEF) tank on the diesel models enabling additional
ground clearance.
The trucks are very connected, with options that
include OnStar®, Commercial Link, a built-in OnStar®
4G LTE™ Wi-Fi® Hotspot (requires a paid data plan),
as well as Inductive Charging for capable Portable
Wireless Devices and Bluetooth® capability. They also
support the Apple® CarPlay™ software feature and
Android™ Auto™ application.
Additional highlights include:
• A modular front on the trucks enables easier
mounting of a snowplow.
• Advanced cooling system for vehicles equipped
with the Duramax® 6.6L — RPO L5P. Cooling
capacity is increased by use of a larger radiator,
an immense cooling fan, and by improving the air
induction system. A dual-path intake system
draws dense, cool air through both the hood
scoop and the front grille in order to optimize
performance.
• Available 120 V alternating current power outlet
located at the rear of the box. It can be used to
plug in electrical equipment that uses a maximum
of 150 watts.
Page 2 June, 2019 Bulletin No.: 19-NA-091
• Available Autotrac Active 2-speed transfer case
on 4WD models that electronically controls
“4 Auto” mode.
• Available dual alternators on both engine options
make it easy to power any accessories needed for
commercial applications.
• Available Power Up/Down Tailgate (Silverado)
that raises or lowers using the key fob, interior
button or the touchpad on the tailgate.
• Silverado provides BedSteps located in front of
the rear wheel openings allowing easier access
from the side of the vehicle. The Sierra is
equipped with the same equipment, however they
are known as Bed side steps. Both complement
the integrated CornerSteps in the rear bumper of
the vehicles that have increased in size also to
improve access to the cargo area.
5286472
• GMC’s innovative and exclusive MultiPro Tailgate
is standard on SLT, AT4, and Denali models and
can be configured and used in six different ways,
including as a step and a load stop for long items.
5318201
• Other features include an easy access engine
coolant block heater outlet, easy to fill diesel
exhaust fluid (DEF) tank with its opening inside of
the fuel door.
• Sierra has 12 corner tie-downs.
• Silverado has 12 fixed tie-down rings, with the
corner rings rated at 500 pounds (227 kg) and the
ability to add up to nine accessory tie downs.
• Vehicles have a Trailering Info Label placed on the
driver’s door jamb which identifies the truck’s
specific trailering information, including curb
weight, GVWR, GCWR, maximum payload,
maximum tongue weight and rear GAWR.
• Vehicles equipped with the Duramax® 6.6L V-8
Turbocharged engine and the 10-speed automatic
transmission provide a 52 percent increase in
maximum towing capability to 35,500 pounds
(16,103 kg) on properly equipped models.
Brakes
ABS Description and Operation
The electronic brake control module (EBCM) and the
brake pressure modulator are serviced separately. The
brake pressure modulator uses a four circuit
configuration to control hydraulic pressure to each
wheel independently.
Depending on options, the following vehicle
performance enhancement systems may be provided:
• ABS
• Traction Control
• Stability Control
• Dynamic Rear Proportioning
• Hill Descent Control System
• Hill Hold Start Assist
• Hydraulic Brake Assist
• Intelligent Brake Assist
Bulletin No.: 19-NA-091 June, 2019 Page 3
• Trailer Brake Control System
• Trailer Sway Control
ABS
When wheel slip is detected during a brake application,
an ABS event occurs. During ABS braking, hydraulic
pressure in the individual wheel circuits is controlled to
prevent any wheel from slipping as needed. A separate
hydraulic line and specific solenoid valves are provided
for each wheel. The ABS can decrease, hold, or
increase hydraulic pressure to each wheel. The ABS
does not increase hydraulic pressure above the amount
which is transmitted by the master cylinder during
braking. During an ABS braking event, a series of rapid
pulsations may be felt in the brake pedal.
ABS Activation Sequence
The typical ABS activation sequence is as follows:
• Pressure Hold: The EBCM closes the isolation
valve and keeps the dump valve closed in order to
isolate the slipping wheel when wheel slip occurs.
This holds the pressure steady on the brake so
that the hydraulic pressure does not increase or
decrease.
• Pressure Decrease: If a pressure hold does not
correct the wheel slip condition, a pressure
decrease occurs. The EBCM decreases the
pressure to individual wheels as needed during
deceleration when wheel slip occurs. The isolation
valve is closed and the dump valve is opened. The
excess fluid is stored in the accumulator until the
pump can return the fluid to the master cylinder or
fluid reservoir.
• Pressure Increase: After the wheel slip is
corrected, a pressure increase occurs. The EBCM
increases the pressure to individual wheels as
needed during deceleration in order to reduce the
speed of the wheel. The isolation valve is opened
and the dump valve is closed. The increased
pressure is delivered from the master cylinder.
Traction Control
When drive wheel slip is noted, the EBCM will enter
Traction Control (TC) mode. First, the EBCM requests
the engine control module (ECM) to reduce the amount
of torque to the drive wheels via a serial data message.
The ECM reduces torque to the drive wheels and
reports the amount of delivered torque. If the engine
torque reduction does not reduce drive wheel slip, the
EBCM will actively apply the brakes on the slipping
drive wheel. During TC braking, hydraulic pressure in
each drive wheel circuit is controlled to prevent the
drive wheels from slipping. The EBCM commands the
pump motor and appropriate solenoid valves ON and
OFF to apply brake pressure to the slipping wheel. TC
can be manually disabled or enabled by pressing the
TC switch.
Stability Control
Stability Control provides added stability during
aggressive maneuvers. Yaw rate is the rate of rotation
about the vehicle’s vertical axis. The stability control is
activated when the EBCM determines that the desired
yaw rate does not match the actual yaw rate as
measured by the yaw rate sensor. The desired yaw rate
is calculated by the EBCM using the following inputs:
steering wheel position, vehicle speed and lateral
acceleration. The difference between the desired yaw
rate and the actual yaw rate is the yaw rate error, which
is a measurement of oversteer or understeer. When a
yaw rate error is detected, the EBCM attempts to
correct the vehicle’s yaw motion by applying brake
pressure to one or more of the wheels. Stability control
activations generally occur in turns during aggressive
driving. When braking during stability control activation,
the brake pedal may pulsate.
Dynamic Rear Proportioning
The dynamic rear proportioning is a control system that
replaces the mechanical proportioning valve. Under
certain driving conditions the EBCM will reduce the rear
wheel brake pressure by commanding the appropriate
solenoid valves ON and OFF.
Hill Descent Control
The Hill Descent Control system allows a smooth and
controlled hill descent in rough terrain without the driver
needing to touch the brake pedal. The vehicle will
automatically decelerate to a low speed and remain at
that speed while activated. Some noise or vibration
from the brake system may be apparent when the
system is active. The descent control system may be
activated, if equipped, by pressing the button on the
console. To activate, press the button when traveling at
speeds of less than 30 mph (50 km/h). To deactivate,
press the button on the console, the brake pedal, or the
accelerator. Descent control enables the vehicle to
descend using the ABS to control each wheel’s speed.
If the vehicle accelerates without driver input, the
system automatically applies the brakes to slow the
vehicle down to the desired speed.
Hill Hold Start Assist
The Hill Hold Start Assist allows the driver to launch the
vehicle without a roll back while moving the foot from
the brake pedal to the accelerator pedal. The EBCM
calculates the brake pressure, which is needed to hold
the vehicle on an incline and locks that pressure for a
certain time by commanding the appropriate solenoid
valves ON and OFF when the brake pedal is released.
Hill hold start assist is activated when the EBCM
determines that the driver wishes to move the vehicle
up-hill, either forward or in R.
Hydraulic Brake Assist
The hydraulic brake assist function is designed to
support the driver in emergency braking situations. The
EBCM receives inputs from the brake pressure sensor
and when it senses an emergency braking situation, it
will actively increase the brake pressure to a specific
maximum.
Intelligent Brake Assist
Intelligent brake assist is designed to provide limited
braking to help prevent front and rear low speed
collisions. The EBCM receives inputs from the brake
pedal position sensor, wheel speed sensors, short
range radar and ultrasonic sensors in order to detect a
collision. When the EBCM calculates a possible
collision, it will actively increase the hydraulic brake
pressure to apply the brakes.
Page 4 June, 2019 Bulletin No.: 19-NA-091
Trailer Brake Control System
A trailer brake control system is used to control the
amount of trailer braking power that is made available
to trailers with brakes that require a controlled output
electrical signal for actuation. The trailer brake control
system determines the trailer brake type (Electric Brake
or Electric Over Hydraulic Brake) automatically.
Trailer Sway Control
Trailer sway control will detect any vehicle yaw
instability, caused by an attached trailer. When
instability is detected, the EBCM attempts to correct the
vehicle’s yaw motion by applying brake pressure to one
or more of the wheels as needed. The engine torque
may be reduced also, if it is necessary to slow down the
vehicle.
Engine 6.6L V8 — RPO L8T
Overview
5318268
5319758
Typical views of the 2020 6.6L V8 gasoline engine
This new, more powerful engine is being produced by
General Motors for use in the new 2500HD, 3500HD
pickup trucks. It is equipped with spark ignited direct
injection (SIDI) for greater performance and increased
fuel efficiency, with 22 percent more torque and up to
18 percent more towing capability when compared to
the previous 6.0L V8 — RPO L96 gasoline engine.
Engine Features and Specifications
• Bore/Stroke: 4.064-inches (103.25 mm) /
3.858-inches (98 mm).
• Compression Ratio: 10.75:1
• Cylinder Block: Cast iron with nodular iron
main caps.
• Cylinder Head: The cylinder heads are made of
cast aluminum for lighter weight and rapid heat
dissipation, with overhead-valve, two valves per
cylinder and variable valve timing.
• Electronic Ignition System: The electronic
ignition system produces and controls the high
energy secondary spark. This spark ignites the
compressed air/fuel mixture at precisely the
correct time, providing optimal performance, fuel
economy, and control of exhaust emissions. The
ECM collects information from the crankshaft
position sensor and camshaft position sensor to
control the sequence, dwell, and timing of the
spark.
• Engine Oil Capacity with Filter: 8 Quarts (7.6 L)
Engine Oil Capacity without Filter:
7.5 Quarts (7.1 L)
• Firing Order: 1-8-7-2-6-5-4-3
• Fuel System: The fuel system is an electronic
returnless on-demand design, which reduces the
internal temperature of the fuel tank by not
returning hot fuel from the engine to the fuel tank.
Bulletin No.: 19-NA-091 June, 2019 Page 5
• Fuel: GM recommends the use of TOP TIER
Gasoline to keep the engine clean and reduce
deposits.
• Horsepower: 401 hp (299 kW) @ 5200 RPM
(SAE certified).
Torque: 464 lb-ft (629 Nm) @ 4000 RPM
(SAE certified).
Engine Controls — Components
Some of the engine controls components and their
operation are as follows:
Camshaft Position Actuator System
The camshaft position actuator system is used for a
variety of engine performance enhancements. These
enhancements include lower emission output through
exhaust gas recirculation (EGR) control, a wider engine
torque range, improved fuel efficiency, and improved
engine idle stability. The CMP actuator system which is
controlled by the ECM, accomplishes these
enhancements by controlling the valve timing relative to
piston position.
Camshaft Position Actuator System Operation
The ECM sends a pulse width modulated signal to a
CMP actuator solenoid in order to control the amount of
engine oil flow to a camshaft actuator passage. There
are 2 different passages for oil to flow through, a
passage for CAM advance and a passage for CAM
retard. The camshaft actuator is attached to the front of
the camshaft, and is hydraulically operated in order to
change the angle of the camshaft relative to the
crankshaft position.
Camshaft Position Sensor
The camshaft position sensor (CMP) detects magnetic
flux changes between the four narrow and wide tooth
slots on the reluctor wheel. The camshaft position
sensor provides a digital ON/OFF DC voltage of varying
frequency per each camshaft revolution. The ECM will
recognize the narrow and wide tooth patterns to identify
camshaft position, or which cylinder is in compression
and which is in exhaust. The information is then used to
determine the correct time and sequence for fuel
injection and ignition spark events.
Crankshaft Position Sensor
The crankshaft position sensor (CKP) is an internally
magnetic biased digital output integrated circuit sensing
device. The sensor detects magnetic flux changes of
the teeth and slots of the reluctor wheel on the
crankshaft. The reluctor wheel is spaced at 60-tooth
spacing, with two missing teeth for the reference gap.
The reference gap is used to identify the crankshaft
position at each start-up. The ECM uses each
crankshaft position signal pulse to determine
crankshaft speed position, to determine the camshaft
relative position to the crankshaft, to control camshaft
phasing, and to detect cylinder misfire.
Electronic Ignition System
The electronic ignition (EI) system produces and
controls the high energy secondary spark. This spark
ignites the compressed air/fuel mixture at precisely the
correct time, providing optimal performance, fuel
economy, and control of exhaust emissions. The ECM
utilizes information from the CKP, CMP and knock
sensor (KS) to control the sequence, dwell, and timing
of the spark.
Engine Misfire Detection
The crankshaft position sensor is used to determine
when an engine misfire is occurring. The camshaft
position sensor is used to determine which cylinder is
misfiring. By monitoring variations in the crankshaft
rotation speed for each cylinder, the ECM is able to
detect individual misfire events. For accurate detection
of engine misfire, the ECM must distinguish between
crankshaft deceleration caused by actual misfire and
deceleration caused by rough road conditions.
EVAP System
The EVAP system limits fuel vapors from escaping into
the atmosphere. Fuel tank vapors are allowed to move
from the fuel tank, due to pressure in the tank, through
the EVAP vapor tube, into the EVAP canister. Carbon in
the canister absorbs and stores the fuel vapors. Excess
pressure is vented through the vent hose and EVAP
vent solenoid valve to the atmosphere. The EVAP
canister stores the fuel vapors until the engine is able to
use them. At an appropriate time, the ECM will
command the EVAP purge solenoid valve ON, allowing
engine vacuum to be applied to the EVAP canister.
With the normally open EVAP vent solenoid valve OFF,
fresh air is drawn through the vent solenoid valve and
the vent hose to the EVAP canister. Fresh air is drawn
through the canister, pulling fuel vapors from the
carbon. The air/fuel vapor mixture continues through
the EVAP purge tube and EVAP purge solenoid valve
into the intake manifold to be consumed during normal
combustion. The ECM uses several tests to determine
if the EVAP system is leaking or restricted.
Heated Oxygen Sensor
The ECM controls a closed loop air/fuel metering
system in order to provide the best possible
combination of driveability, fuel economy, and emission
control. The ECM monitors the heated oxygen sensor
(HO2S) signal voltage and adjusts the fuel delivery
based on the signal voltage while in closed loop. The
short term fuel trim values change rapidly in response
to the HO2S signal voltages. These changes fine tune
the engine fueling. The long term fuel trim values
change in response to trends in the short term fuel trim.
The long term fuel trim makes coarse adjustments to
fueling in order to re-center and restore control to short
term fuel trim.
Ignition Coils
Each ignition coil has an ignition 1 voltage circuit and a
ground circuit. The ECM supplies a low reference and
an ignition control circuit. Each ignition coil contains a
solid state driver module. The ECM will command the
ignition control circuit ON, which allows the current to
flow through the primary coil windings. When the ECM
commands the ignition control circuit OFF, this will
interrupt current flow through the primary coil windings.
The magnetic field created by the primary coil windings
will collapse across the secondary coil windings, which
induces a high voltage across the spark plug
electrodes.
Page 6 June, 2019 Bulletin No.: 19-NA-091
Knock Sensor
The Knock Sensor (KS) system is used by the ECM to
control the ignition timing for the best possible
performance while protecting the engine from
potentially damaging levels of detonation, also known
as spark knock. The KS system uses one or two flat
response 2-wire sensors. The sensor(s) use
piezo-electric crystal technology that produces an AC
voltage signal of varying amplitude and frequency
based on the engine vibration or noise level and
provides that signal to the ECM.
Fuel System
Overview
The fuel system is an electronic returnless on-demand
design which reduces the internal temperature of the
fuel tank by not returning hot fuel from the engine to the
fuel tank. Reducing the internal temperature of the fuel
tank results in lower evaporative emissions. An electric
turbine style fuel pump attaches to the fuel tank fuel
pump module inside the fuel tank. The fuel pump
supplies fuel through the fuel feed pipe to the high
pressure fuel pump. The high pressure fuel pump
supplies fuel to a variable-pressure fuel rail. Fuel enters
the combustion chamber through precision multi-hole
fuel injectors. The high pressure fuel pump, fuel rail
pressure, fuel injection timing, and injection duration
are controlled by the ECM.
Electronic Returnless Fuel System Operation
The electronic returnless fuel system controls fuel
delivery using a microprocessor. It functions as an
electronic replacement for a traditional, mechanical fuel
pressure regulator. The pressure relief regulator valve
within the fuel tank provides an added measure of over
pressure protection. Desired fuel pressure is
commanded by the ECM, and transmitted to the K111
fuel pump driver control module via a GMLAN serial
data message. A fuel pressure sensor located on the
fuel feed pipe provides the signal used by the ECM for
Closed Loop fuel pressure control.
Fuel Pressure Sensor
The fuel pressure sensor is a serviceable 5 V, 3-pin
device. It is located on the fuel feed line forward of the
fuel tank. The ECM provides a 5 V circuit and a low
reference circuit. The sensor provides the fuel pressure
signal to the ECM, which is used for Closed Loop fuel
pressure control.
Fuel Pump Driver Control Module
The K111 fuel pump driver control module is a
serviceable GMLAN module. The fuel pump driver
control module receives the desired fuel pressure
signal from the ECM and controls the fuel pump located
within the fuel tank to achieve the desired fuel pressure.
The fuel pump driver control module controls the
in-tank fuel pump by providing varying AC voltage to
the 3 phase motor inside the fuel pump.
Fuel Pump
The fuel pump is mounted in the fuel tank fuel pump
module reservoir. The fuel pump is a 3 phase electric
pump. Fuel is pumped to the high pressure fuel pump
at a pressure that is based on feedback from the fuel
pressure sensor. The fuel pump delivers a constant
flow of fuel even during low fuel conditions and
aggressive vehicle maneuvers. The fuel pump flex pipe
acts to dampen the fuel pulses and noise generated by
the fuel pump.
Fuel Pump — High Pressure
The high fuel pressure necessary for direct injection
(DI) is supplied by the high pressure fuel pump. The
high pressure fuel pump is mounted on the rear of the
engine under the intake manifold and is driven by a
tri-lobe cam on the camshaft. The high pressure fuel
pump also regulates the fuel pressure using an actuator
in the form of an internal solenoid-controlled valve.
Fuel Tank Fuel Pump Module
The electric turbine style fuel pump attaches to the fuel
tank fuel pump module inside the fuel tank and supplies
fuel through the fuel feed pipe to the high pressure fuel
pump. The fuel tank fuel pump module contains a
reverse flow check valve. The check valve maintains
fuel pressure in the fuel feed pipe in order to prevent
long cranking times. The fuel tank fuel pump module
consists of the following major components:
• Fuel Level Sensor: The fuel level sensor
consists of a float, a wire float arm, and a ceramic
resistor card. The position of the float arm
indicates the fuel level. The fuel level sensor
contains a variable resistor which changes
resistance in correspondence with the position of
the float arm. The ECM monitors the signal circuit
of the fuel level sensor in order to determine the
fuel level and sends the information to the
instrument panel cluster to control the fuel gauge.
• Fuel Pump and Reservoir Assembly
• Pressure Relief Regulator Valve: The pressure
relief regulator valve replaces the typical fuel
pressure regulator used on a mechanical
returnless fuel system. The valve is closed during
normal vehicle operation. The pressure relief
regulator valve is used to vent pressure during hot
soaks and also functions as a fuel pressure
regulator in the event of the fuel pump driver
control module defaulting to 100% commanded
output of the fuel pump.
• Fuel Strainer
• Primary Jet Pump: The primary jet pump is
located in the fuel tank fuel pump module. Fuel
pump flow loss, caused by vapor expansion in the
pump inlet chamber, is diverted to the primary jet
pump through a restrictive orifice located on the
pump cover. The primary jet pump fills the
reservoir of the fuel tank fuel pump module.
Bulletin No.: 19-NA-091 June, 2019 Page 7
Fuel Rail Assembly
The fuel rail assembly attaches to each cylinder head.
The fuel rail distributes high pressure fuel to the fuel
injectors. The fuel rail assembly consists of the direct
fuel injectors and the fuel rail pressure sensor. The fuel
rail pressure sensor transmits fuel pressure and
temperature information by serial data using the
Society of Automotive Engineers (SAE) J2716 Single
Edge Nibble Transmission (SENT) protocol.
Fuel Injectors
The fuel injector assembly is an inside opening
electrical magnetic injector. The injector has six
precision machined holes that generate a cone shaped
oval spray pattern. The fuel injector has a slim
extended tip in order to allow a sufficient cooling jacket
in the cylinder head. The fuel injectors are mounted in
the cylinder head beneath the intake ports and spray
fuel directly into the combustion chamber. Direct
injection requires very high fuel pressure due to the fuel
injector’s location in the combustion chamber.
Engine Oil — 6.6L Gasoline
Specification
5108021
Use full synthetic engine oils that meet the dexos®1
APPROVED – GEN 2 specification. Engine oils that
have been approved by GM as meeting the dexos®1
specification are marked with the dexos®1
APPROVED – GEN 2 logo.
Viscosity Grade
Use SAE 5W-30 viscosity grade engine oil for the 6.6L
V8 gasoline engine. In an area of extreme cold, where
the temperature is colder than −20°F (−29°C), use SAE
0W-30 oil. An oil of this viscosity grade will provide
easier cold starting for the engine at extremely cold
temperatures.
Engine 6.6L V8 — RPO L5P
Overview
5122972
Typical view of the Duramax® 6.6L V8 — RPO L5P
This is a turbocharged diesel engine produced by
DMAX which is a joint venture between GM and Isuzu
in Moraine, Ohio for use in the new 2500HD, 3500HD
pickup trucks and other GM vehicles.
Engine Features and Specifications
• Bore/Stroke: 4.055-inches (103 mm) /
3.8976-inches (99 mm).
• Compression Ratio: 16.0:1
• Cooling System: Cooling system capacity is
30.8 qt (29.15 L).
• Connecting Rods: The connecting rods are
one-piece hot forged steel. The connecting rods
and caps are of a fractured split design to improve
durability and reduce internal friction. The
connecting rod small end is tapered cut for
reduced weight and improved durability.
• Crankshaft: The crankshaft is a forged steel
design with five main bearings. Crankshaft thrust
is controlled by the number 5 bearing.
Page 8 June, 2019 Bulletin No.: 19-NA-091
4663083
• Cylinder Block: The engine block utilizes a deep
skirt design for increased rigidity. The cylinders
are positioned in a 90 degree “V” orientation with
the number one cylinder being the right front. The
block is induction hardened for increased
durability. The crankshaft bearing caps are
cross-bolted to enhance structural rigidity.
• Cylinder Head: The cylinder heads are made of
aluminum for lighter weight and rapid heat
dissipation. There are 4 valves per cylinder and
the ports are of a high swirl design for improved
combustion. The cylinder head gaskets consist of
an all steel laminated construction.
• Engine Covers: There is a front engine cover
and a flywheel housing, both are made of
aluminum. The full bell flywheel housing is cross
bolted to the upper oil pan. The flywheel housing
also provides a crossover passage for engine
coolant. The front engine cover houses the gear
train and provides a mounting surface for the
cooling fan pulley assembly.
• Engine Oil Capacity with Filter: Capacity is
10 qt (9.5 L).
• EGR System: The EGR system is used to reduce
the amount of nitrogen oxide (NOx) emission
levels caused by high combustion temperatures.
At temperatures more than 1,371°C (2,500°F),
oxygen and nitrogen combine to form NOx.
Introducing small amounts of exhaust gas back
into the combustion chamber displaces the
amount of oxygen entering the engine. With less
oxygen in the air/fuel mixture, the combustion
pressures are reduced, and as a result,
combustion temperatures are decreased,
restricting the formation of NOx. Exhaust gas
recirculation is water cooled for improved
reduction in NOx emissions.
• Exhaust Manifold: Cast nodular iron with steel
pipe extension.
• Firing Order: 1-2-7-8-4-5-6-3
• Fuel System: Direct injection (DI) with
high-pressure common rail. In the diesel engine,
air alone is compressed in the cylinder. Then, after
the air has been compressed, a charge of fuel is
sprayed into the cylinder and ignition occurs, due
to the heat of compression.
5152404
• Fuel Type: GM recommends the use of TOP
TIER Diesel Fuel to keep the engine clean and
reduce engine deposits. Use Ultra-Low Sulfur
Highway Diesel Fuel and/or B20 biodiesel. Fuels
with a biodiesel content up to 20% by volume may
be used (e.g., named B20). Always look for the
TOP TIER Diesel Fuel Logo at the fuel dispenser.
– DO NOT use diesel fuel with more than 15 ppm
sulfur.
– DO NOT use off-highway diesel fuel, also known
as off-road diesel fuel.
• Glow Plugs: The engine utilizes eight ceramic
glow plugs. Compared to conventional glow plugs,
ceramic glow plugs enable greater efficiency
through higher temperature capability and faster
preheating time. However, ceramic glow plugs are
much more sensitive to damage than conventional
glow plugs. Damage can occur to the glow plug
and not be visible, causing future engine failure.
Therefore, ceramic glow plugs are considered
one-time-use. Be sure to discard and replace with
NEW whenever a ceramic glow plug is removed
from the cylinder head. If the cylinder head is ever
removed with the ceramic glow plugs, the ceramic
glow plugs must all be replaced with new.
Bulletin No.: 19-NA-091 June, 2019 Page 9
Whenever installing a new ceramic glow plug,
clean the glow plug bore with a proper tool as
outlined in the service procedure. Carbon build-up
in the glow plug bore can damage the ceramic
glow plugs.
• Horsepower: SAE-certified 445 horsepower
(332 kW).
Torque: SAE-certified 910 lb-ft (1,234 Nm).
• Intake Airflow Valve: The intake airflow valve is
a throttle plate actuator and is used to achieve
high exhaust gas recirculation rates. It increases
the pressure difference between exhaust and
intake so that the appropriate exhaust quantity
can be mixed with the intake air.
• Maximum Braking Speed: 4,800 RPM.
• Maximum Powered Speed: 3,450 RPM.
• Oil Cooler: The oil cooler lowers engine
temperature by cooling the oil with engine coolant.
Engine coolant is directed from the water pump to
the oil cooler by a coolant tube. The oil filter
attaches directly to the oil cooler.
• Oil Pump: The oil pump is gear driven directly
from the crankshaft. The oil pump drive gear is a
slip fit to the crankshaft.
• Piston: The pistons are a full-floating design. The
piston pins are a slip fit in the bronze bushed
connecting rod and are retained in the piston by
round wire retainers. The pistons have a piston
cooling oil channel cast inside. These cooling oil
channels utilize an oil jet located at the bottom of
the cylinder bore to direct oil into the piston
channel. There are two compression rings and
one oil control ring. There is a groove machined
into the pistons between the first and second
compression rings. This groove reduces
compression ring leakage by providing an empty
space for expanding gases, reducing the
combustion gas pressure on the second
compression ring.
• Turbocharger: The turbocharger is water cooled
for improved durability. It is a variable vane style.
The pitch of the turbine vanes can be changed by
ECM command to meet varying conditions.
• Upper Oil Pan: A single piece cast aluminum
upper oil pan contributes to crankshaft and block
rigidity while reducing overall weight.
• Valvetrain: The engine utilizes a mechanical
roller lifter for valve operation. One rocker arm
operates two valves simultaneously through a
valve bridge.
• Water Pump: The water pump is gear driven for
improved reliability.
Duramax® After-Run Feature
A new after-run feature, specifically engineered for use
following a demanding towing situation is an additional
new technology for the Duramax engine. The after-run
allows the engine to keep running for up to 15 minutes
to allow it to cool down using the fan and circulating the
engine coolant. If the driver puts the truck in P when an
after-run situation is needed, an alert will appear on the
DIC directing them to keep the engine running for cool
down. Should the driver choose to ignore the message
and exit the vehicle, the truck will restart on its own via
remote start mode for cool-down. At that point the
customer can walk away and the truck will turn itself
OFF when the engine reaches an acceptable
temperature.
Duramax® Cooling System
Helping cool the Duramax® engine is a massive
28-inch (71 cm) diameter fan with variable fan speed,
which is 2.5-inches (6.35 cm) larger than the current
fan. The ECM controls the fan speed by sending a
pulse width modulated (PWM) signal to the cooling fan
control module. The cooling fan control module varies
the voltage drop across the cooling fan motor in relation
to the PWM signal, which allows the cooling fan to
operate at variable speeds.
Elevated Idle
The engine has a cold temperature high idle feature
which elevates the engine idle speed from base idle to
approximately 1,050 to 1,100 RPM when outside
ambient temperatures are colder than 32°F (0°C), and
the engine coolant temperature (ECT) is colder than
150°F (65°C). This feature enhances heater
performance by increasing the ECT faster.
Engine Coolant Heater
The coolant heater operates using 110 V alternating
current from an external power source and is designed
to warm the coolant in the engine block area for
improved starting in weather conditions that are colder
than 0°F (−18°C). Vehicles with an engine block heater
should be plugged in at least four hours before starting.
An internal thermostat in the plug-end of the cord may
exist, which will prevent engine coolant heater
operation at temperatures warmer than 0°F (−18°C).
The coolant heater also helps reduce fuel consumption
when a cold engine is warming up. The unit is equipped
with a detachable AC power cord. A weather shield on
the cord is provided to protect the plug when not in use.
Exhaust Brake
The Duramax® / Allison® combination incorporates an
integrated engine exhaust brake, which leverages the
engine’s backpressure and the Heavy Duty’s driveline
components to help control the speed of the truck and
trailer while descending, reducing the need to use
service brakes on long, steep grades. The exhaust
brake is also tied to the cruise control system, allowing
a set speed to easily be maintained, even over hilly
terrain.
Page 10 June, 2019 Bulletin No.: 19-NA-091
Fuel System Diagram
Fuel System Diagram — RPO L5P
5294832
Legend
(1) Auxiliary Fuel Tank (Equipped with
RPO N2N)
(2) Fuel Filter Assembly with Water in Fuel
Sensor
(3) E11A Fuel Heater/Water in Fuel Sensor
(4) B48 Fuel Temperature Sensor
(5) B47 Fuel Pressure Sensor
(6) Q67 Exhaust Aftertreatment Fuel Injector
(7) B47B Fuel Rail Pressure Sensor
(8) Fuel Injection Fuel Rail Assembly
(9) Q18B Fuel Rail Pressure Regulator 2
(10) Q18A Fuel Pressure Regulator 1
(Located in Fuel Injection Pump)
(11) G18 High Pressure Fuel Pump
(12) Q17 Fuel Injector(s)
(13) Fuel Cooler
(14) Fuel Tank — Primary
(15) G12A Fuel Pump — Primary
(16) G12B Fuel Pump — Secondary
(Equipped with RPO N2N)
(17) K111 Fuel Pump Driver Control Module
Fuel Tank — Auxiliary
For vehicles equipped with dual fuel tanks, the auxiliary
fuel tank is located in the rear of the vehicle. The fuel
tank is held in place by 2 metal straps that attach to the
frame. The fuel tank is molded from high density
polyethylene.
Fuel Filter Assembly
The fuel filter assembly is located near the left frame
rail and contains the following components: fuel filter/
water separator, fuel heater, fuel temperature sensor,
water in fuel sensor.
Fuel Heater
The fuel heater is controlled by the ECM. When the
temperature of the fuel is less than a calibrated value,
the ECM will command the fuel heater relay ON. When
the relay is ON, battery voltage is supplied to the fuel
heater to assist in cold weather operation.
Fuel Temperature Sensor
The fuel temperature sensor is a thermistor that is
located in the fuel filter assembly. The ECM monitors
the fuel temperature sensor through the fuel pump
driver control module in order to calculate the
temperature of the fuel entering the fuel injection pump.
Bulletin No.: 19-NA-091 June, 2019 Page 11
Fuel Pressure Sensor
The fuel pressure sensor is located in the fuel feed
pipe. The fuel pressure sensor monitors the fuel
pressure in the fuel line. The ECM monitors the voltage
signal from the fuel pressure sensor. The sensor
provides a fuel pressure signal to the ECM, which is
used to provide fuel pressure control.
Exhaust Aftertreatment Fuel Injector
The exhaust aftertreatment fuel injector, also known as
an indirect fuel injector is located on the passenger side
frame rail. The exhaust aftertreatment fuel injector is
used to inject fuel into the exhaust system to generate
the required heat needed by the diesel oxidation
catalyst to function properly.
Dual Fuel Rail Pressure Sensor
The fuel rail pressure sensor is a dual analog sensor
that provides two fuel rail pressure signals to the ECM
and is located in the end of the fuel rail assembly. The
ECM provides a 5 V reference voltage on the 5 V
reference circuit and ground on the low reference
circuit. The ECM receives a varying signal voltage on
both the fuel rail pressure sensor and fuel rail pressure
sensor 2 signal circuits. The ECM monitors the voltage
on both of the fuel rail pressure sensor circuits and
compares the values to determine if the sensors are
accurate. When the fuel pressure is high, the fuel rail
pressure sensor signal voltage is high and the fuel rail
pressure sensor 2 signal voltage is low. When the fuel
pressure is low, the fuel rail pressure sensor signal
voltage is low and the fuel rail pressure sensor 2 signal
voltage is high.
Fuel Rail Assembly
The left and right fuel rails are attached to the cylinder
heads. The fuel rails distribute pressurized fuel to the
fuel injectors through the fuel lines.
Fuel Pressure Regulator 1
The ECM controls the fuel rail pressure using two pulse
width modulated fuel rail pressure regulators. Fuel
pressure regulator 1 is located in the fuel injection
pump and meters the amount of fuel that enters the
high pressure side of the pump. From the high pressure
pump, the fuel moves to the fuel rail through a high
pressure steel line. The fuel rail distributes high
pressure fuel to all 8 fuel injectors.
Fuel Pressure Regulator 2
The ECM controls the fuel rail pressure using two pulse
width modulated fuel rail pressure regulators. Fuel
pressure regulator 2 is located on the rear of the driver
side fuel rail and meters the amount of fuel being
returned to the fuel tank. The ECM varies the pulse
width modulated voltage to the fuel pressure regulator 2
to relieve excessive fuel pressure which returns to the
fuel tank. When the ignition is OFF, fuel pressure
regulator 2 opens to bleed off the pressure in the
fuel rail.
High Pressure Fuel Pump
The high pressure fuel pump is a mechanical pump.
The high pressure fuel pump is located at the front of
the engine below the intake manifold. The high
pressure fuel pumps provides high pressure fuel to the
fuel rail at a specified pressure regulated by the fuel
pressure regulators.
Fuel Injectors
A fuel injector is a solenoid device, controlled by the
ECM, that meters pressurized fuel to a single engine
cylinder. Fuel from the fuel injector tip is sprayed
directly into the combustion chamber on the
compression stroke of the engine. The fuel injectors are
located above each cylinder and deliver fuel directly
into the cylinder. Each injector has a high pressure fuel
pipe from the fuel rail and a return line.
Fuel Cooler
The fuel cooler is located under the vehicle. The
returning fuel flows through the cooler in order to
reduce the fuel temperature before returning it to the
vehicle’s fuel tank.
Fuel Tank — Primary
The primary fuel tank is located on the left side of the
vehicle. The fuel tank is held in place by 2 metal straps
that attach to the frame. The fuel tank is molded from
high density polyethylene.
Fuel Pump — Primary
The primary fuel pump is mounted in the primary fuel
tank module reservoir.
Fuel Pump — Secondary
The fuel transfer pump is located in the auxiliary (rear)
fuel tank, (if equipped with N2N).
Fuel Pump Driver Control Module
The fuel pump driver control module is located under
the vehicle, mounted to the bracket above the spare
tire. If this component is replaced, the Fuel Pump Driver
Control Module Configuration must be performed.
Water in Fuel Sensor
The water in fuel sensor monitors for the presence of
water in the diesel fuel. When water is present, the fuel
pump driver control module detects low voltage on the
signal circuit and sends a message to the ECM. The
ECM sends a serial data message to the instrument
panel cluster to display the WATER IN FUEL SERVICE
REQUIRED message.
Page 12 June, 2019 Bulletin No.: 19-NA-091
Exhaust Aftreatment System
Emission Control System Architecture — RPO L5P
4863779
Legend
(1) E41 ECM w/Baro Sensor
(2) Reductant Control Module, CAN
Interface
(3) DEF Pressure Sensor
(4) DEF Heaters — to Reductant Control
Module
(5) DEF Pump — to Reductant Control
Module
(6) DEF Continuous Level Sensor — to
Reductant Control Module
(7) DEF Temperature Sensor — to
Reductant Control Module
(8) DEF Quality Sensor — to Reductant
Control Module
(9) Exhaust Gas Temperature Sensor [5x]
(10) HC Injector
(11) DPF Differential Pressure Sensor
(12) PM Sensor, CAN Interface
(13) DPF
(14) DOC
(15) NOx Sensor [2x] — CAN Interface
(16) SCR
(17) DEF Injector
(18) Close Coupled DOC
Overview
The diesel exhaust aftertreatment system is designed
to reduce the levels of hydrocarbons (HC), carbon
monoxide (CO), oxides of nitrogen (NOx), and
particulate matter (PM) in the engine exhaust gases.
Reducing these pollutants to acceptable levels is
achieved using the following components:
1. Close Coupled Diesel Oxidation Catalyst
(DOC): The close coupled DOC functions similar
to the catalytic converter used with gasoline
engines. As with all catalytic converters, the DOC
must be hot in order to effectively convert the
exhaust HC and CO into CO2 and H2O. Proper
DOC function requires the use of ultra-low sulfur
diesel (ULSD) fuel containing less than 15 ppm
sulfur.
2. Selective Catalyst Reduction (SCR): Diesel
engines are more fuel efficient and produce less
HC and CO than gasoline engines, however they
generate much higher levels of NOx. In order to
meet the current NOx limits, an SCR catalyst,
along with reductant, is used to convert NOx into
N2, CO2, and H2O.
3. Diesel Oxidation Catalyst (DOC): In addition to
reducing emissions, the DOC also generates the
exhaust heat needed by the SCR to properly
function. Exhaust gas temperature sensors are
located upstream and downstream of the DOC. By
monitoring the temperature differential between
these sensors, the ECM is able to confirm DOC
light-off. Light-off is confirmed by a DOC output
temperature that is greater than its input
temperature. In order to generate the high exhaust
temperatures needed for regeneration, the
aftertreatment system increases exhaust
temperatures by injecting diesel fuel into the
exhaust gases entering the DOC. This is
accomplished by means of a hydrocarbon injector
(HCI) upstream of the DOC in the exhaust system.
Bulletin No.: 19-NA-091 June, 2019 Page 13
4. Diesel Particulate Filter (DPF): The DPF
captures diesel exhaust gas particulates, also
known as soot, preventing their release into the
atmosphere. This is accomplished by forcing
particulate-laden exhaust through a filter substrate
consisting of thousands of porous cells. Half of the
cells are open at the filter inlet but are capped at
the filter outlet. The other half of the cells are
capped at the filter inlet and open at the filter outlet.
This forces the particulate-laden exhaust gases
through the porous walls of the inlet cells into the
adjacent outlet cells trapping the particulate matter
(PM). The DPF is capable of removing more than
90% of particulate matter, or soot carried in the
exhaust gases.
DEF
Depending on the information being referenced,
reductant is also identified as diesel exhaust fluid (DEF)
which is a mixture of specifically blended aqueous
urea solution of 32.5% high purity urea (Pharmaceutical
Grade Urea) and 67.5% deionized water. Within the
SCR, exhaust heat converts the urea into ammonia
(NH3) that reacts with NOx to form nitrogen, CO2, and
water vapor. Optimum NOx reduction occurs at SCR
temperatures of more than 480°F (250°C). At lower
temperatures, NH3 and NOx may react to form
Ammonium Nitrate (NH4NO3) which can lead to
temporary deactivation of the SCR catalyst. To prevent
this, the ECM will suspend DEF injection when the
exhaust temperature is less than a calibrated minimum.
DEF Heaters for Cold Weather Operation
A 32.5% solution of urea with 67.5% deionized water
will begin to crystallize and freeze at 12°F (−11°C). At
this ratio, both the urea and water will freeze at the
same rate, ensuring that as it thaws, the fluid does not
become diluted, or over concentrated. The freezing and
thawing of DEF will not cause degradation of the
product. There are two DEF heaters in the system. DEF
Heater 1 is in the DEF reservoir and DEF Heater 2 is in
the supply line to the DEF injector. The K115 Reductant
Control Module monitors the B214 Reductant
Temperature Sensor located within the reservoir in
order to determine if the DEF temperature is below its
freeze point. If the module determines that the DEF
may be frozen, it energizes the DEF heaters. DEF
pump operation is disabled for a calibrated amount of
time to allow the heaters an adequate amount of time to
thaw the frozen DEF. Once the thaw time period
expires, the module energizes the DEF pump to
circulate warm DEF back to the reservoir to speed
thawing. The ECM looks for an increase in the DEF
temperature to verify that the DEF reservoir heater is
working.
DEF Injector
The ECM energizes the DEF injector in order to
dispense a precise amount of reductant upstream of
the SCR in response to changes in exhaust NOx levels.
The signal from NOx Sensors 1 and 2 allow the ECM to
accurately control the amount of DEF supplied to the
SCR. If more DEF is supplied to the SCR than is
needed for a given NOx level, the excess DEF results
in what is called ammonia slip where significant levels
of ammonia exit the SCR. Since the NOx sensors are
unable to differentiate between NOx and ammonia, the
ammonia slip will cause NOx Sensor 2 to detect higher
NOx levels than actually exist.
DEF Level
The DEF level must be maintained for the vehicle to run
properly. As the DEF level becomes low, warnings are
displayed on the DIC. These warnings will increase in
intensity as the DEF level is reduced. As the tank nears
empty, vehicle speed will be limited in a series of steps.
At least 2 gallons (7.57 L) of DEF must be added to
release the speed limitation.
DEF Reservoir Components
The DEF system reservoir components consist of the
following: :
• An electrically-operated DEF pump
• An integrated B213A Reductant Level Sensor 1
and B214 Reductant Temperature Sensor
• K115 Reductant Control Module
• B295 Reductant Quality Sensor
• Reductant system heaters
• An electrically controlled DEF injector which is
external to the reservoir.
Exhaust Gas Temperature (EGT) Sensor
The engine uses exhaust gas temperature
management to maintain the SCR catalyst within the
optimum NOx conversion temperature range of
390–750°F (200–400°C). The ECM monitors the EGT
sensors located upstream and downstream of the SCR
in order to determine if the SCR catalyst is within the
temperature range where maximum NOx conversion
occurs.
NOx Sensor
The ECM uses two smart NOx sensors to monitor the
exhaust NOx levels. The first NOx sensor is located at
the turbocharger outlet and monitors the engine out
NOx. The second NOx sensor is located in the exhaust
pipe downstream of the SCR and monitors NOx levels
exiting the aftertreatment system. The smart NOx
sensors communicate with the ECM over the serial
data line. The smart NOx sensors consist of two
components, the NOx module and the NOx sensor
element that are serviced as a unit. The NOx sensors
incorporate an electric heater that is controlled by the
NOx module to quickly bring the sensors to operating
temperature.
Particulate Matter Sensor
The PM sensor determines the amount of particulates
(soot) in the diesel exhaust gas exiting the tailpipe by
monitoring the collection efficiency of the DPF and to
aid in OBD-II emission diagnostics. The PM sensor is
similar to the heated oxygen sensor with a ceramic
element but also includes an individually calibrated
control unit. The PM sensor sensing element includes
two comb-shaped inter-digital electrodes, a heater and
a positive temperature coefficient (PTC) resistor for
temperature measurement.
The operation of the PM sensor is based on the
electrical conductivity characteristic of the soot. As the
exhaust gas flows over the sensing element, soot is
Page 14 June, 2019 Bulletin No.: 19-NA-091
absorbed in the combs between the electrodes,
eventually creating a conductive path. When the path is
formed, it generates a current based on the voltage
being applied to the element. The measurement
process continues until a preset current value is
reached. To avoid misleading readings, the sensor
operates on a “regenerative” principle, where the soot
is cleaned off by heating up the element to burn off the
carbon, before the measurement phase begins. The
amount of regenerations is based on vehicle strategy.
The cumulative PM sensor current readings are used to
determine the amount of soot concentration in the
exhaust gas, and determine the collection efficiency of
the DPF and if a regeneration is needed.
Regeneration Process
A number of engine and exhaust aftertreatment
components are required to function together to
perform the regeneration process. The engine
components are the fuel injectors, turbocharger, Intake
Air (IA) valve, fuel pressure control, and the intake air
heater (IAH).
DEF Recommendation — Storage and
Transfer
DEF Recommendation
5138259
API Certified Diesel Exhaust Fluid Logo
• General Motors DEF is an aldehyde free, NOx
reducing treatment. It is a mixture of 32.5% high
purity synthetic urea and 67.5% deionized water.
GM DEF meets the stringent ISO 22241 standard
for purity and concentration. GM DEF is a stable,
colorless, non-flammable, non-toxic primary
component used to help convert NOx, an
environmental pollutant, into harmless nitrogen
and water. Use Diesel Exhaust Fluid
GM PN 19286291, in Canada 88862660 or DEF
that meets the International Organization for
Standardization ISO 22241 specification or
displays the API Certified Diesel Exhaust Fluid
Mark (meets API certification requirements).
Classified as minimum risk for transportation.
• ACDelco® DEF is an aldehyde free, NOx reducing
treatment. It is a mixture of 32.5% high purity
synthetic urea and 67.5% deionized water.
ACDelco® DEF meets the stringent ISO 22241
standard for purity and concentration. ACDelco®
DEF is a stable, colorless, non-flammable,
non-toxic primary component used to help convert
NOx, an environmental pollutant, into harmless
nitrogen and water. It meets API regulations, and
meets or exceeds GM OE specifications.
Classified as minimum risk for transportation.
Storage and Transfer
DEF has a shelf life of approximately 24 months, but
when exposed to sunlight or prolonged exposure to
temperatures warmer than 75°F (23.8°C), the nitrogen
in DEF begins to volatilize into ammonia gas and can
reduce shelf life. Once volatilized, it will not go back into
suspension and the percentage of urea in the product
decreases to less than the optimum 32.5%. Fresh DEF
has a slightly pungent smell of ammonia. After
extended exposure to temperatures warmer than 75°F
(23.8°C), the ammonia scent grows stronger, indicating
nitrogen has vaporized, changing the urea-to-water
ratio of the product. Because DEF is highly reactive to
many metals, it must be stored in stainless steel,
polypropylene or high-density polyethylene (HDPE)
storage tanks. All pumps, valves and fittings must be
DEF compatible and used only to transfer DEF.
Bulletin No.: 19-NA-091 June, 2019 Page 15
Warning Light
5152580
When there is an issue with the DEF such as a low fluid
level or fluid contamination, the DEF Warning Light will
illuminate, a DIC message will display and a chime will
sound. To avoid vehicle speed limitations, fill the DEF
tank at the first opportunity after a Low Fluid Level
warning message displays.
Engine Oil — 6.6L Diesel
Ash Loading
Ash is a non-combustible by-product occurring from
normal oil consumption. Low ash content engine oil
(CJ-4 or CK-4) is required for these diesel engine
equipped vehicles because of the exhaust
aftertreatment system. Ash accumulation will eventually
cause a restriction in the DPF. Being non-combustible,
ash is not burned off during regeneration. A DPF that is
ash loaded will need to be replaced.
Specification
5123610
Engine oil with the letters CJ-4 or CK-4 are required for
the Duramax® 6.6L diesel engine. The CJ-4 or CK-4
designation can appear either alone or in combination
with other American Petroleum Institute (API)
designations, such as API CJ-4/SL. These letters show
API levels of quality.
Viscosity Grade
Use SAE 15W-40 viscosity grade engine oil. In an area
of extreme cold, where the temperature is colder than
0°F (−18°C), use SAE 5W-40. An oil of this viscosity
grade will provide easier cold starting for the engine at
extremely cold temperatures.
Head-Up Display
5323981
Both vehicles offer an available multicolor 15-inch
(381 mm) diagonal Head-Up Display (HUD) to help
keep the driver’s eyes on the road by conveniently
Page 16 June, 2019 Bulletin No.: 19-NA-091
projecting key information directly onto the windshield
such as speed, active safety information, available
Navigation and an inclinometer that measures grade.
Supplemental Inflatable Restraint
System
Overview
The supplemental inflatable restraint (SIR) system
supplements the protection offered by the seat belts.
The SIR system contains an Inflatable Restraint
Sensing and Diagnostic Module (SDM), air bags, seat
belt pretensioner (anchor and retractor), and impact
sensors. The SDM is a microprocessor and the control
center for the SIR system. The SDM determines the
severity of a collision with the assistance of impact
sensors located at strategic points on the vehicle.
When the SDM detects a collision, it will process the
information provided by the sensors to further support
air bag or pretensioner deployment. The SDM will
deploy the air bags and pretensioners if it detects a
collision of sufficient force. If the force of the impact is
not sufficient to warrant air bag deployment, the SDM
may still deploy the seat belt pretensioners. The SDM
contains a sensing device that converts vehicle velocity
changes to an electrical signal. The SDM compares
these signals to calibrated values stored in its memory.
If the signals exceed a calibrated value, the SDM will
determine the severity of the impact and either cause
current to flow through the frontal deployment loops
deploying the frontal air bags and pretensioners, or it
will deploy the pretensioners only. The SDM
continuously monitors the deployment loops and the
SIR system electrical components for malfunctions and
illuminates the SIR system AIR BAG indicator if a fault
is detected.
Air Bags
These vehicles contain 7 air bags. The 7 air bags are
located in the steering wheel (dual air bags), instrument
panel (passenger side) (dual air bags), driver side seat
inboard side, driver side seat outboard side, passenger
side (seat), left roof rail, right roof rail. Air bags contain
a housing, inflatable air bag, two initiating devices (if
dual air bags), a canister of gas generating material
and, in some cases, stored compressed gas. The
deployment loops supply current to deploy the air bags.
The steering wheel and passenger instrument panel air
bags have two stages of deployment, which varies the
amount of restraint to the occupant according to the
collision severity. For moderate frontal collisions the air
bags deploy at less than full deployment which consists
of stage 1. For more severe frontal collisions a full
deployment is initiated which consists of stage 1 and
stage 2. The current passing through the air bags ignite
the material in the canister producing a rapid
generation of gas and is some cases, the release of
compressed gas. The gas produced from this reaction
rapidly inflates the air bag. Once the air bag is inflated it
quickly deflates through the air bag vent holes and/or
the bag fabric. A shorting bar (if equipped) is located in
the air bag connector.
Impact Sensors
There are multiple impact sensors which may be
located in the front of the vehicle, in the front doors or
on the B-pillar, and on the C-pillar depending on the
vehicle configuration. The front of vehicle, B-pillar, and
C-pillar impact sensors contain a sensing device which
monitors vehicle acceleration to detect collisions that
are severe enough to warrant air bag deployment. The
front door impact sensors contain a sensing device
which monitors the door cavity air pressure change to
detect side collisions that are severe enough to warrant
air bag deployment. It is important when working on
components in the door to make sure any items which
have a sealing impact on the door (water deflector,
exterior door handle, speaker, door harness grommet,
or sealing strip) are securely fastened when reinstalled.
The impact sensors are not part of the deployment
loop, but instead provide input to the SDM.
Seat Belt Pretensioners
Important: Once a pyrotechnic pretensioner is
activated it must be replaced.
The pyrotechnic pretensioner is the most sophisticated
type of pretensioning device. The seat belt pretensioner
(driver and passenger) consist of a housing, seat belt
retractor (located in the B-pillar), seat belt anchor
(located in the seat), seat belt webbing, an initiator, and
a canister of gas generating materials. The initiator is
part of the seat belt pretensioner deployment loop.
When the vehicle is involved in a collision of sufficient
force, the SDM causes current to flow through the seat
belt deployment loops to the initiator. Current passing
through the initiator ignites the material in the canister
producing a rapid generation of gas. The gas produced
from this reaction deploys the seat belt pretensioners
which removes all of the slack in the seat belts.
Depending on the severity of the collision, the seat belt
pretensioners may deploy without the frontal air bags
deploying, or they will deploy immediately before the
frontal air bags deploy. A shorting bar (if equipped) is
located in the connector.
Snow Plow
The air bag system was designed to work properly
under a wide range of conditions, including snow
plowing with vehicles that have the optional snow plow
prep package — RPO VYU
DO NOTchange or defeat the snow plow’s “tripping
mechanism” because it can damage the snow plow and
the vehicle, and may cause an air bag deployment.
Suspension — Front
Short long arms independent front suspension with
torsion bars.
Suspension — Rear
Semi-elliptic three-stage multi-leaf spring.
Bulletin No.: 19-NA-091 June, 2019 Page 17
Tire Rotation — Tire and Loading
Information Label
Tire and Loading Information Label
A vehicle-specific Tire and Loading Information label is
attached to the center pillar (B-pillar). The Tire and
Loading Information label shows the number of
occupant seating positions, and the maximum vehicle
capacity weight in pounds and kilograms. The Tire and
Loading Information label also shows the size of the
original equipment tires and the recommended cold tire
inflation pressures. There is also important loading
information on the vehicle Certification/Tire label. It may
show the Gross Vehicle Weight Rating (GVWR) and the
Gross Axle Weight Rating (GAWR) for the front and
rear axles.
Tire Rotation
Tires should be rotated every 7,500 mi (12,000 km).
Tires are rotated to achieve a uniform wear for all tires.
The first rotation is the most important. The outer tire on
a dual wheel setup generally wears faster than the
inner tire. Adjust the front and rear tires to the
recommended inflation pressure on the Tire and
Loading Information label after the tires have been
rotated.
Tire Rotation Pattern — Single Rear Wheels
5318508
Use this rotation pattern when rotating the tires if the
vehicle has single rear wheels.
Tire Rotation Pattern — Polished Forged Dual
Aluminum Wheels
5152010
Vehicles with polished forged aluminum dual wheels
have three unique wheels; a front, a rear outer and a
rear inner. These wheels cannot be rotated to another
position, however, they can be rotated from left to right
to the same position.
Use this rotation pattern when rotating the tires if the
vehicle has polished forged aluminum dual rear wheels.
The spare wheel can be used in any position in the
event of a flat tire, and can be rotated with the rear
inner wheels. After the flat tire is repaired, if the spare is
not on one of the inner rear positions, it must be
replaced by the correct wheel in the front or rear outer
positions.
Tire Rotation Pattern — Dual Rear Wheels
5151982
Use this rotation pattern when rotating the tires if the
vehicle has dual rear wheels (except polished forged
aluminum wheels).
Page 18 June, 2019 Bulletin No.: 19-NA-091
Trailer Detection
With RPO U1D
The K68 Trailer Lighting Control Module is supplied
with battery voltage as well as ignition voltage and is
permanently grounded. The trailer lighting control
module constantly monitors for trailer connection
status, this is accomplished through the lighting circuits
of the trailer to determine if a trailer is connected. With
the key OFF, the K68 Trailer Lighting Control Module
will periodically pulse the lighting circuits of the trailer to
verify it is still connected. Depending on the
configuration of the trailer lights, the trailer lights may
periodically flash as part of the trailer theft deterrent
function. These flashes correspond to when the K68
Trailer Lighting Control Module pulses the lighting
circuits to ensure the trailer is still connected and is
considered normal. When a trailer is connected, the
K68 Trailer Lighting Control Module senses the trailer
connection and alerts the driver by requesting a trailer
profile setup through the Trailering App, which is
displayed on infotainment screen (P17 Info Display
Module). If a trailer is disconnected with the ignition
ON, the vehicle will display multiple trailer lighting
message faults until a trailer is reconnected or the
ignition is cycled.
Trailering Mirrors
Overview
The trailering mirrors have been redesigned with
improved perimeter lighting. New, larger and more
functional door-mounted trailering mirrors are standard
on all 2500HD and 3500HD models. The mirrors extend
and retract using a four-bar-link system that makes for
smooth operation, whether done with power or
manually. The surface area of the mirrors is larger, for a
greater field of view compared to the current model,
and an available power extension feature makes it
easier to adjust the view from the driving position. New
for 2020 is the forward-facing spot lamp on each mirror
that shines light at about a 45-degree angle, providing
illumination on the job site or camp site. There also are
side-view cameras mounted within the mirror housings,
and when equipped, mirror-mounted puddle lamps and
two rearward-facing spot lamps are also available.
Extending
5326383
If equipped, grasp the mirror housing firmly and pull
back in one motion, arching slightly toward the rear of
the vehicle.
Retracting
5326390
To return the mirror to its original position, reverse the
motion.
Power Extending Mirrors
If equipped, press the power extend button to fully
extend the mirror. Press it again to retract.
Bulletin No.: 19-NA-091 June, 2019 Page 19
Trailering Systems
The available Advanced Trailering System (Silverado)
and ProGrade Trailering System (Sierra) offer
additional and new technologies. The in-vehicle
trailering system features an available total of 15
camera views (requires an installed accessory
camera), such as HD Surround Vision and other unique
views including a transparent trailer view feature to help
provide added confidence when towing and a hitch
view camera used when connecting the trailer to the
vehicle.
5303297
Transparent trailer camera view.
5303357
Trailer hitch camera view.
5324568
Sierra bed-view camera.
5324544
Silverado High Country with 5th wheel.
Trailering — Vehicle Weight Ratings
Curb Weight
Curb Weight is the weight of a vehicle without the
driver, passengers or cargo but including the maximum
capacity of fuel, oil, coolant and other items of standard
equipment.
Page 20 June, 2019 Bulletin No.: 19-NA-091
Gross Axle Weight Rating
Note: It is important to remember that a vehicle’s
GAWR is not a measurement of how much weight
each axle is actually carrying at any given time. The
actual amount of weight each axle is carrying is the
gross axle weight or GAW.
A vehicle’s Gross Axle Weight Rating (GAWR) is the
specific weight determined by the manufacturer to be
the maximum allowable weight that can be placed on
an individual axle. Front and rear axles have individual
GAWR. The GAWR is a weight limit for each of the
vehicle’s axles which is determined by the
manufacturer. A vehicle’s axles should never be loaded
beyond the manufacturer’s listed GAWR. The GAWR
includes the weight of the vehicle, passengers, cargo
and trailer tongue weight (if equipped). All of this weight
is distributed between two axles.
Gross Combined Weight Rating
Note: It is important to remember that the GCWR is
not an actual measurement of the weight of a tow
vehicle and a trailer, but rather the combined
maximum weight limit that the manufacturer has set
for the two vehicles once attached.
A specific vehicle’s Gross Combined Weight Rating
(GCWR) is based on parameters established by
chassis manufacturers. The manufacturer makes an
assessment in accordance with SAE International test
protocols, determining maximum GCWR. Additionally,
the OEM runs stringent tests based on internal
requirements which may include testing total GCWR
braking capability using only the towing vehicle chassis
braking system. GCWR is the total weight of the truck
pulling the trailer and the trailer itself. The truck chassis
dictates proper GCWR for safe operation of the
combination truck and trailer. GCWR is the total
allowable weight of the completely loaded vehicle and
trailer including fuel, passengers, cargo, equipment,
and accessories. Do not exceed the GCWR for the
vehicle.
Gross Combined Weight Rating — Calculating
To check that the weight of the vehicle and trailer are
within the GCWR for the vehicle, follow these steps:
• Start with the “curb weight” from the trailering
information label.
• Add the weight of the trailer loaded with cargo and
ready for the trip.
• Add the weight of all passengers.
• Add the weight of all cargo in the vehicle.
• Add the weight of hitch hardware such as a draw
bar, ball, load equalizer bars and sway bars.
• Add the weight of any accessories or aftermarket
equipment added to the vehicle.
The resulting weight cannot exceed the GCWR of the
vehicle.
The gross combined weight can also be confirmed by
weighing the truck and trailer on a public scale. The
truck and trailer should be loaded for the trip with
passengers and cargo.
Gross Vehicle Weight
Gross Vehicle Weight (GVW) is the total weight of the
truck and payload at a point in time and will vary. The
GVW includes the vehicle’s listed curb weight, cargo,
equipment, trailer tongue weight (if equipped) and
passengers. Vehicle options, passengers, cargo, and
equipment reduce the maximum allowable tongue
weight the vehicle can carry, which also reduces the
maximum allowable trailer weight.
Gross Vehicle Weight Rating
Note: It is important to remember that the GVWR is
not a measurement of how much a vehicle actually
weighs. A vehicle’s actual weight is the gross
vehicle weight, or GVW.
A truck’s Gross Vehicle Weight Rating (GVWR) is the
maximum weight rating established by the chassis
manufacturer. The OEM will determine the GVWR
based on test results and vehicle dynamic performance
to ensure a safe, reliable truck. Safety standards that
apply to braking, vehicle stability, and chassis
manufacturer internal standards for durability, dynamic
stability and handling can restrict GVWR to less than
the sum of the gross axle weight ratings (GAWR) for
that vehicle. The GVWR is calculated by adding the
vehicle’s listed curb weight, the weight of any optional
accessories, cargo, the trailer tongue weight (if
equipped) and passengers.
Transmission — 6-Speed 6L90
Automatic
Overview
5324137
The Hydra-Matic™ 6L90 6-speed — RPO MYD is a
fully automatic, rear-wheel drive, electronic-controlled
transmission. It consists primarily of a 4-element torque
converter, an integral fluid pump and converter
housing, a single and double planetary gear set, friction
and mechanical clutch assemblies, and a hydraulic
pressurization and control system. There are four
Bulletin No.: 19-NA-091 June, 2019 Page 21
variants of the transmission, all based on torque
capacity. Architecture is common between the variants,
and component differences are primarily related to size.
Transmission General Description
The 6-speed 6L90 has a 4-element torque converter
that contains a pump, a turbine, a pressure plate
splined to the turbine, and a stator assembly. The
torque converter acts as a fluid coupling to smoothly
transmit power from the engine to the transmission. It
also hydraulically provides additional torque
multiplication when required. The pressure plate, when
applied, provides a mechanical direct drive coupling of
the engine to the transmission.
The planetary gear sets provide the 6 forward gear
ratios and reverse. Changing gear ratios is fully
automatic and is accomplished through the use of a
transmission control module (TCM) located inside the
transmission. The TCM receives and monitors various
electronic sensor inputs and uses this information to
shift the transmission at the optimum time.
The TCM commands shift solenoids and variable bleed
pressure control solenoids to control shift timing and
feel. The TCM also controls the apply and release of
the torque converter clutch which allows the engine to
deliver the maximum fuel efficiency without sacrificing
vehicle performance. All the solenoids, including the
TCM, are packaged into a self-contained control
solenoid valve assembly.
The hydraulic system primarily consists of a vane-type
pump, 2 control valve body assemblies, converter
housing and case. The pump maintains the working
pressures needed to stroke the clutch pistons that
apply or release the friction components. These friction
components, when applied or released, support the
automatic shifting qualities of the transmission.
The friction components used in this transmission
consist of 5 multiple disc clutches. The multiple disc
clutches combine with one mechanical sprag clutch to
deliver 7 different gear ratios, 6 forward and one
reverse, through the gear sets. The gear sets then
transfer torque through the output shaft.
Transmission — 10-Speed 10L1000
Automatic
Notice: The all-new Allison® / General Motors
10-Speed Transmission can be Serviced at
Authorized Chevrolet and GMC Dealers.
Overview
5343851
Right Side
5343900
Left Side
The Allison® Branded 10-speed 10L1000 automatic
transmission — RPO MGM or MGU, manufactured by
General Motors, combines enhanced performance, fuel
economy, greater operational flexibility, and improved
driver comfort and control, with an industry-leading
reputation for uptime and reliability. Designed for
high-performance and low-maintenance, the 10-speed
coupled with the Duramax® 6.6L diesel engine
provides superior power delivery and productivity. The
Page 22 June, 2019 Bulletin No.: 19-NA-091
new transmission is tested and validated in partnership
with Allison® Transmission. Each transmission will
deliver its legendary quality and durability. The
Duramax® / Allison® powertrain standard axle ratio has
been reduced to 3.42:1, reducing engine speed,
enhancing refinement and efficiency. Duramax®
equipped vehicles with the 10-speed transmission are
available as 2WD or 4WD.
Transmission General Description
The transmission is a fully automatic, 10-speed,
rear-wheel drive electronically controlled transmission.
The ten speed ratios are generated using four simple
planetary gearsets, two brake clutches, and four
rotating clutches. The resultant on-axis transmission
architecture utilizes a squashed torque converter, an
off-axis pump and four close coupled gearsets. The
four rotating clutches have been located forward of the
gearsets to minimize the length of oil feeds which
provides for enhanced shift response. There are
different variants of the transmission, all based on
torque capacity. Architecture is common between the
variants, and component differences are primarily
related to size.
The transmission architecture features a case with an
integral bell housing for enhanced powertrain stiffness.
A unique pump drive design allows for off-axis
packaging very low in the transmission. The pump is a
variable vane type which effectively allows for two
pumps in the packaging size of one. This design and
packaging strategy not only enables low parasitic
losses and optimum priming capability but also
provides for ideal oil routing to the controls system, with
the pump located in the valve body itself. The
transmission control module (TCM) is externally
mounted, enabling packaging and powertrain
integration flexibility. The TCM utilizes three speed
sensor signals providing enhanced shift response and
accuracy. The transmission enables solid fuel
efficiency, superior performance and outstanding
vehicle safety.
The 4-element torque converter contains a pump, a
turbine, a pressure plate splined to the turbine, and a
stator assembly. The torque converter acts as a fluid
coupling to smoothly transmit power from the engine to
the transmission. It also hydraulically provides
additional torque multiplication when required. The
pressure plate, when applied, provides a mechanical
direct drive coupling of the engine to the transmission.
The planetary gear sets provide the 10 forward gear
ratios and reverse. The TCM receives and monitors
various electronic sensor inputs and uses this
information to shift the transmission at the
optimum time.
The hydraulic system primarily consists of an off-axis
gear-driven variable vane-type pump next to the valve
body, and 2 control valve body assemblies. The pump
maintains the working pressures needed to stroke the
clutch pistons that apply or release the friction
components. These friction components, when applied
or released, support the automatic shifting qualities of
the transmission.
The friction components used in this transmission
consist of 6 multiple disc clutches. The multiple disc
clutches deliver 11 different gear ratios, 10 forward and
one reverse, through the gear sets. The gear sets then
transfer torque through the output shaft.
Power Take-Off
An all new factory integrated, engine-driven Power
Take-Off (PTO) is available and eliminates the need for
an aftermarket unit. Exclusively offered with the
10-speed transmission on select diesel models, it’s the
first fully integrated PTO system in the HD truck
segment, with the PTO’s drive gear operated via chain
to direct engine power. And because it is engine-driven
rather than turbine-driven, the PTO can be used while
the vehicle is idling. A button inside the cab enables the
PTO, and a mode selector allows adjustment of load
and torque output.
Transfer Case — Autotrac 2-Speed
Overview
If equipped, the Autotrac 2-speed transfer case on
4WD models electronically controls “4 Auto” mode,
allowing the truck to seamlessly shift between 2WD
and 4WD based on road conditions.
Autotrac helps the driver to select the ideal 4WD mode,
depending on road conditions, using electronic controls
to make the process seamless. The Autotrac 2-speed
transfer case offers four transfer case modes, allowing
the driver to select the ideal mode for specific on-road
or off-road conditions. To select a mode, the driver will
either push a button or use a rotary knob (depending on
equipment) located on the instrument panel to the left
of the steering wheel.
Operation
The Magna Powertrain (MP) model 3025— RPO NQH
is a 2-speed automatic, active transfer case (ATC). The
MP 3025 ATC provides 5 modes, Auto 4WD, 4HI, 4LO,
2HI and NEUTRAL (N). The Auto 4WD position allows
the capability of an active transfer case, which provides
the benefits of on-demand torque biasing wet clutch
and easy vehicle tuning through software calibrations.
The software calibrations allow more features such as
flexible adapt ready position and clutch preload torque
levels. The technology allows for vehicle speed
dependent clutch torque levels to enhance the
performance of the system. For example, the system is
calibrated to provide 0–5 lb-ft (0–6.78 Nm) of clutch
torque during low speed, low engine torque operation,
and predetermined higher torque for 25 mph (40 km/h)
and greater. This prevents crow-hop and binding at low
speeds and provides higher torque biases at higher
vehicle speeds, in order to enhance stability.
Bulletin No.: 19-NA-091 June, 2019 Page 23
5326341
Typical view of Sierra AT4 Autotrac 2 controls.
• 2 Hi: For normal operation on paved roads where
there is no loss of traction, this mode allows the
vehicle to operate as 2WD to help save wear on
4WD components. When this mode is selected,
the front axle is disengaged and power is
distributed only to the rear axle.
• 4 Auto: If road conditions frequently vary
between high and low-traction areas, 4 Auto can
help automatically distribute torque to the front
axle by anticipating the need for additional
traction, helping to improve handling and control.
In this mode, the front axle is engaged but the
transfer case uses an electronically controlled
clutch to manage torque sent to each axle. The
transfer case automatically adjusts the clutch to
help provide improved traction, stability and
control.
• 4 Hi: High-range 4WD is designed to help
increase traction when driving over loose, slippery
or demanding terrain, such as off-road conditions,
deep sand or snow. This mode is NOT designed
for use on dry surfaces or roads with good
traction, so it is important to shift out of 4 Hi as
soon as road conditions improve.
• 4 Low: Low-range 4WD engages gearing within
the transfer case to provide more torque to the
wheels for off-road driving, such as in deep sand,
mud or snow. In severe off-road scenarios, 4 Low
is designed to help give the driver more control of
the vehicle’s speed when crossing obstacles or
rocks, or climbing and descending steep grades.
This mode should NOT be utilized at speeds over
45 mph (72 km/h) and is NOT designed for use on
dry surfaces or roads with good traction.
• Neutral: Additionally, the vehicle may include N,
which disengages the driveline to allow the truck
to be towed behind another vehicle (also known
as dinghy towing). Use this range ONLY when
the vehicle needs to be towed.
Page 24 June, 2019 Bulletin No.: 19-NA-091
Turbocharger System Description
Variable Vane Turbocharger Overview
4584300
Legend
(1) Turbine Housing
(2) Lower Vane Ring
(3) Vane Ring Assembly Spacer
(4) Upper Vane Ring Assembly
(5) Adjusting Ring Assembly
(6) V-Band Nut
(7) V-Band
(8) Compressor Housing Bolt
(9) Core Assembly
(10) Linkage Assembly
(11) Linkage Assembly Nut
(12) Compressor Housing O-Ring
(13) Actuator Nut
(14) Compressor Housing
(15) Actuator
The turbocharger increases engine power by pumping
compressed air into the combustion chambers, allowing
a greater quantity of fuel to combust at the optimal air/
fuel ratio. The turbine spins as exhaust gas flows out of
the engine and over the turbine blades, and turns the
compressor wheel at the other end of the turbine shaft,
pumping more air into the intake system. This is a
BorgWarner™ single stage, water cooled, variable
geometry turbocharger (VGT) capable of producing
220 kPa (31.9 psi) boost pressure.
The ECM communicates with the turbocharger vane
position actuator via the controller area network (CAN)
bus to control the turbocharger vanes. The smart
actuator incorporates a brushless motor and is
mounted on top of the turbocharger. It is connected to
the vanes by a linkage rod. The vanes are used to vary
the amount of boost pressure and can control the boost
pressure independent of engine speed. The vanes
mount to a unison ring which is rotated to change the
vane angle. The ECM will vary the vane angle which
adjusts the boost dependent upon the load
requirements of the engine.
When the actuator arm is in the vertical top rest position
the turbocharger vanes are fully open. When the
actuator arm is in the horizontal bottom of travel
position the turbocharger vanes are fully closed.
The turbocharger vanes are normally open when the
engine is not under load. However, the ECM will often
close the turbocharger vanes to create back pressure
to drive exhaust gas through the Exhaust Gas
Bulletin No.: 19-NA-091 June, 2019 Page 25
Recirculation (EGR) valve as required. At extreme cold
temperatures, the ECM may close the vanes at low
load conditions in order to accelerate engine coolant
heating.
The turbocharger is also utilized as a component of the
exhaust brake system. Under certain conditions, the
ECM will automatically close the turbocharger vanes to
build back pressure in the exhaust, which reduces
engine speed and slows the vehicle without applying
the brakes.
During regeneration, the ECM will vary the
turbocharger vanes to assist with the exhaust system
warm-up, and to maintain proper engine exhaust
temperatures needed to properly regenerate the DPF.
Each time the ignition is turned OFF, the turbocharger
vane position actuator performs a learn procedure. The
actuator arm sweeps the turbocharger vanes from fully
open to fully closed to obtain a count value. This value
is compared to the previous value to ensure proper
vane position. Following the learn sweep the actuator
sweeps the vanes two more times to clean off
combustion soot.
Upfitter Integration Group
Important: When adding non OE content to a
vehicle, contact the GM Upfitter Integration Group
for assistance if needed.
1. To visit the GM Upfitter Integration Group Home
Page, Go to: https://www.gmupfitter.com/
Scroll to the bottom of the page and click on:
Contact Us / Request Data
2. A request form will appear in a new window. To
request technical assistance from the GM Upfitter
Integration Group, complete and submit the form.
Special Tools
The following new tools were released for the
2020 Silverado / Sierra 2500HD and 3500HD pickup
trucks:
Special Tools — Tool Number and Description
Tool Number Description
EN-52793 Front Crankshaft Seal Installer (6.6L L8T)
EN-52794 Rear Crankshaft Seal Installer (6.6L L8T)
Training Courses
Training Courses — Description — Number and Course Name
Description Number and Course Name
New Model Launch #10320.18H — 2020 Chevrolet Silverado and GMC Sierra
2500HD/3500HD New Model Launch (T1CXH Truck)
Automatic Transmission #17041.85V — 10L1000 Allison Branded® HydraMatic™
Transmission
Version Information
Version 1
Modified Released June 10, 2019
Page 26 June, 2019 Bulletin No.: 19-NA-091
Trademark Footnotes
ACDelco® is a registered trademark of General
Motors LLC
Allison® is a registered trademark of Allison
Transmission
Android™ is a trademark of Google LLC .
Android Auto™ is a trademark of Google LLC
Apple® is a registered trademark of Apple Inc.
Bluetooth® is a registered trademark Owned by
Bluetooth SIG, Inc.
BorgWarner™ is a Trademark of Borg-Warner
Corporation
CarPlay™ Software Feature is a trademark of
Apple Inc.
Duramax® is a registered trademark of General
Motors LLC (United States)
Duramax™ is a trademark of General Motors LLC
HydraMatic™ is a Trademark of General
Motors LLC
LTE™ is a trademark of the European
Telecommunications Standards Institute (ETSI)
OnStar® is a registered trademark of OnStar, LLC
Wi-Fi® is the registered trademark of the Wi-Fi
Alliance

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