Diagnostic Tip for DTCs Set at a Low Mileage for 9T45/50/60 Automatic Transmissions – 2020-2022 Buick Cadillac Chevrolet GMC Holden

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Service Bulletin Bulletin No.: 21-NA-169
Date: December, 2021
TECHNICAL
Subject: Diagnostic Tip for DTCs Set at a Low Mileage for 9T45/50/60 Automatic Transmissions
Attention: This bulletin only applies to vehicles with less than 19,000 km (12,000 miles) on the
odometer.
Brand: Model:
Model Year: VIN:
Engine:
Transmission:
(9T45, 9T50 or
9T60
Automatic)
from to from to
Buick
Encore GX 2020 2022
— — —
M3F
Envision 2020 2022 M3T, M3H
Regal 2020 2020 M3D, M3T
Cadillac
XT4
2020 2022
M3H
XT5 M3G
XT6 M3G
Chevrolet
Blazer 2020 2022 M3D, M3T
Equinox 2020 2020 M3D
Malibu 2020 2022 M3E
Trailblazer 2021 2022 M3F
GMC
Acadia
2020 2022
M3H, M3G
Terrain M3H, M3U
Holden Equinox 2020 2020 M3D
Involved Region or Country North America, Middle East, Europe, Australia/New Zealand
Condition
The purpose of this bulletin is to aid the service technician in diagnosing 9T45/50/60
automatic transmissions with low mileage and DTCs current or history related to the
control solenoids and valves. Follow the Service Procedure steps below to determine
repair strategy.
Information
Important: For vehicles equipped with 9T65 transmissions (RPO M3V or M3W), do not
follow this bulletin and refer to Service Bulletin # 20-NA-136.
Please refer to these service publications for resolutions to customer comments prior to
proceeding with this bulletin:
⇒ 18-NA-359: Information on Flashing D in PRNDL and/or Transmission Slip/
Flare on 1-2 Upshift with Zero to Very Light Throttle Input
⇒ 21-NA-038: Humming Noise Heard Coming From Front End of Vehicle When
Driving at Highway Speeds (Blazer)
⇒ 19-NA-023: High Pitch Whine Noise Heard at 32-56 km/h (20-35 mph) in Any
Gear Under Light to Moderate Acceleration (Equinox, Terrain)
⇒ 20-NA-165: Flutter or Boom Noise at 1200 RPM- Service Calibration
(Trailblazer, Encore GX)
⇒ PIT5778A: Vibration Or Boom At 1300 RPM (Equinox, Terrain)
⇒ PIP5697B – DTC P0747 Setting At Engine Start-Up When The Transmission
Is In Park
⇒ 21-NA-118: Vibration Type Noise Heard at Highway Speeds or with Engine
Speed at 1,300-1,500 RPM (XT5, XT6, Blazer, Acadia)
Page 2 December, 2021 Bulletin No.: 21-NA-169
Service Procedure
Step One – DTCs
Check all Modules for DTCs. Records of all DTCs,
Current or History, and Module Located In/On Repair
Order.
Step Two – Fluid Level and Condition Check
Note: Ensure the transmission has enough fluid in it to
safely start the vehicle without damaging the
transmission. With the vehicle off and the transmission
fluid temperature at approximately 20–25°C (68–77°F),
there must be at least enough fluid to drain out of the
fluid level hole. This will ensure that there is enough
fluid in the sump to fill the components once the vehicle
is started.
1. Start the engine.
2. Depress the brake pedal and move the shift lever
through each gear range, pausing for about 3
seconds in each range. Then move the shift lever
back to PARK (P).
3. Allow the engine to idle 500–800 rpm for at least 3
minutes to allow any fluid foaming to dissipate and
the fluid level to stabilize.
4. Release the brake pedal.
5. Keep the engine running and observe the
transmission fluid temperature (TFT) using the
Driver Information Center (DIC) or a scan tool.
Caution: The transmission fluid level must be checked
when the transmission fluid temperature (TFT) is at 85–
95°C (185–203°F). If the TFT is not at this temperature,
operate the vehicle or allow the fluid to cool as
required. Setting the fluid level with a TFT outside this
temperature will result in either an under or over-filled
transmission. TFT 95°C under-filled, TFT 85°C
over-filled. An under-filled transmission will cause
premature component wear or damage. An over-filled
transmission will cause fluid to discharge out the vent
tube, fluid foaming, or pump cavitation.
6. Raise the vehicle on a hoist. The vehicle must be
level, with the engine running and the shift lever in
the PARK range.
7. While the vehicle is idling, remove the oil level set
plug (1). Allow any fluid to drain:
• If the fluid is flowing as a steady stream, wait
until the fluid begins to drip.
• If no fluid comes out, add fluid until fluid
drips out.
8. Record fluid level; overfilled, under-filled, correct
on repair order and how much was needed to fill or
came out:
• If fluid is overfilled, set correct level and retest.
• If fluid is under-filled, inspect for external leaks.
Refer to Fluid Leak Diagnosis in SI.
5840393
9. If fluid level is correct, then check condition of the
fluid:
• The fluid should be red or brown.
• The fluid should be transparent so that objects
or writing can be seen through it. Sample #1 is
an example of acceptable fluid. Sample #2 is an
example of very dark fluid. Sample #3 is an
example of black fluid.
• In addition to checking the fluid color and
transparency, the fluid should be checked for an
odor of burnt fluid. If the fluid is very dark, black,
or has a burnt odor it would indicate clutch
damage has occurred internally in the
transmission and it would need to be removed
from the vehicle and investigated.
• Fluid that is cloudy or milky or appears to be
contaminated with water indicates engine
coolant or water contamination. Refer to the last
version of Service Bulletin 08-07-30-035 for
testing and, if confirmed, find the source of the
coolant/water and repair. Then follow service
manual instructions “engine coolant/water in
transmission” to repair the transmission.
• Inspect the fluid for excessive metal particles or
other debris:
– A small amount of “friction” material is a
“normal” condition.
– A small amount of “metal” from the
manufacturing process is a “normal”
condition. This is observed as fine silver
streaks floating in the fluid.
– If large pieces and/or metal pieces are noted
in the fluid, or the fluid when rubbed between
fingers feels gritty/sandy, it would indicate
hardware damage has occurred internally in
the transmission and it would need to be
removed from the vehicle and investigated.
• Inspect for external leaks. Refer to Fluid Leak
Diagnosis in SI.
– If fluid level and condition are OK, proceed to
next step.
Bulletin No.: 21-NA-169 December, 2021 Page 3
Step Three – Line Pressure Check
Warning: Keep the brakes applied at all times in
order to prevent unexpected vehicle motion.
Personal injury may result if the vehicle moves
unexpectedly.
Note: You may need to remove or disconnect
components in order to gain access to the transmission
line pressure test hole plug.
1. Remove the line pressure test hole plug. Refer to
Automatic Transmission Fluid Pressure Test Hole
Plug Replacement in SI.
2. Install the GE-21867 Pressure Gauge.
3. Start the engine.
4. Verify the Transmission Fluid Pressure = Greater
than 345 kPa (50 psi).
• If pressure is below 50 psi, record on the repair
order and follow SI document for Fluid Pressure
High or Low.
• If above 50 psi, proceed to next step.
5. Turn the engine OFF.
6. Remove the GE-21867 Pressure Gauge.
7. Install and tighten line pressure test hole plug.
Refer to Automatic Transmission Fluid Pressure
Test Hole Plug Replacement in SI.
Step Four – Perform Road Test
Perform step 1-4 first in order to ensure the electronic
transmission components are functioning properly. If
these components are not checked, a simple electrical
condition could be misdiagnosed.
1. Connect the scan tool.
2. Ensure the gear selector is in PARK and set the
parking brake.
3. Start the engine.
4. Verify that the following scan tool data can be
obtained and is functioning properly.
⇒ Refer to Control Module References for typical
data values. Data that is questionable may
indicate a concern.
5. Check the garage shifts:
⇒ Apply the brake pedal and ensure the parking
brake is set.
⇒ Move the gear selector through the following
ranges:
• PARK to REVERSE
• REVERSE to NEUTRAL
• NEUTRAL to DRIVE
• DRIVE to REVERSE
• REVERSE to DRIVE
⇒ Pause 2 to 3 seconds in each gear position.
⇒ Verify the gear engagements are immediate
(less than 2 seconds to complete if transmission
fluid temperature is above 20°C (68°F) and not
harsh. Note that these shifts may be almost
imperceptible in some applications. Using the
scan tool to monitor Transmission ISS,
achieving 0 rpm can be used to check delay in
these cases.
Note: Harsh engagement may be caused by any of the
following conditions:
• High engine idle speed – Compare engine idle
speed to desired idle speed.
• A default condition caused by certain DTCs that
result in maximum line pressure to prevent
clutch slippage.
• Incomplete adapting or incorrect adapting –
Repeat maneuver multiple times to see if shift
quality improves. If it does not and no DTCs
were set, then refer to SI document “Harsh
Garage Shift”.
Note: Delayed engagement may be caused by any of
the following conditions:
• Low idle speed – Compare engine idle speed to
desired idle speed.
• Low fluid level.
• Cold transmission fluid temperature (TFT) –
Use the scan tool to determine TFT.
• Selector linkage – Inspect and adjust as
necessary.
• Incomplete adapting or incorrect adapting –
Repeat maneuver multiple times to see if delay
improves. If it does not and no DTCs were set,
then refer to SI document “Harsh Garage Shift”.
6. Check Upshifts – The TCM calculates the upshift
points based primarily on 2 inputs: throttle position
and vehicle speed. When the TCM determines that
conditions are met for a shift to occur, the TCM
commands the shift by varying current to the
appropriate PC solenoids to control oncoming and
off going clutch pressures.
⇒ Monitor the following scan tool parameters:
• Calc. Throttle Position
• Vehicle Speed
• Engine Speed
• Transmission ISS
• Transmission OSS
• Command Gear
• TCC PC Sol. Pressure Cmd.
• TCC Slip Speed
• TFP Switch 1
• TFP Switch 2
• TFP Switch 3
• TFP Switch 4
• PC Sol. 2 Pressure Cmd.
• PC Sol. 3 Pressure Cmd.
• PC Sol. 4 Pressure Cmd.
• PC Sol. 5 Pressure Cmd.
• Shift Solenoid 1 and 2
1. Place the gear selector in the DRIVE position.
2. Accelerate the vehicle using a steady throttle
position between 15 and 20 percent. Hold the
throttle steady.
Page 4 December, 2021 Bulletin No.: 21-NA-169
3. As the transmission upshifts, there should be a
noticeable shift feel or engine speed change within
1 to 2 seconds of the commanded gear change.
The PC solenoid pressure command should
change to “YES” for the oncoming clutch and the
PC solenoid pressure command should change to
“NO” for the off going clutch.
4. Note any harsh, soft or delayed shifts or slipping.
Note any noise or vibration.
5. The torque converter clutch (TCC) feel may not be
noticeable. In many applications the TCC will apply
after the 1-2 shift and TCC events will not be easily
detected using engine speed. Monitor TCC PC
solenoid pressure command while driving and
check TCC slip speed when the pressure
command indicates that the TCC is commanded to
apply.
6. When the TCC applies, slip speed should be
controlled to below 100 RPM when the
transmission is not shifting and the throttle is held
steady. If the TCC slip exceeds this value for more
than 6 seconds after the TCC PC Sol. Pressure
Command indicates that the TCC is
commanded on:
• Check for DTCs.
• Refer to Torque Converter Diagnosis in SI.
Note: This transmission is equipped with an
electronically controlled capacity clutch (ECCC), which
allows operation of the clutch without fully locking to the
torque converter cover. The clutch maintains a small
amount of slippage, approximately 20 RPM, in 2nd, 3rd,
4th, 5th, and 6th gears, depending on the vehicle
application. ECCC was developed to reduce the
possibility of noise, vibration or chuggle caused by TCC
apply. Full lockup is available at highway speeds on
some applications.
7. Part Throttle Step-in Downshifts:
⇒ Place the gear selector in the DRIVE position.
⇒ Accelerate the vehicle at light throttle (5-10
percent) until 3rd gear is just achieved.
⇒ Quickly increase throttle angle until
commanded gear indicates that a downshift to
2nd gear is commanded.
⇒ Verify that the transmission downshifts within 2
seconds of the throttle movement
⇒ Repeat steps 2 to 4 at higher speed to achieve
4th gear and then step in to command a 4th
gear to 3rd gear downshift.
⇒ Repeat steps 2 to 4 at higher speed to achieve
5th gear and then step in to command a 5th to
4th gear downshift.
⇒ Repeat steps 2 to 4 at higher speed to achieve
6th gear and then step in to command a 6th
gear to 5th gear downshift.
⇒ Note any harsh, soft or delayed shifts or
slipping. Note any noise or vibration.
8. Coasting Downshifts:
⇒ Place the gear selector in the DRIVE position.
⇒ Accelerate the vehicle to 6th gear with the TCC
applied.
⇒ Release the throttle and apply the brakes.
⇒ Verify that the downshifts occur as commanded
by monitoring gear ratio, which should change
after commanded gear changes.
⇒ Note any harsh, soft or delayed shifts or
slipping. Note any noise or vibration.
9. Reverse:
⇒ With the vehicle stopped, move the gear
selector to REVERSE.
⇒ Slowly accelerate the vehicle to a 10-15 percent
throttle position.
⇒ Verify that there is no noticeable slip, noise or
vibration.
10. Road Test Results:
⇒ Diagnostic TIP: If completion of the above tests
are inconclusive to isolate if the transmission
shifting concern(s) are internal transmission or
input/command, can use the control function
feature in GDS2 to command all shifts. If when
using GDS2 to command shifts and
transmission shifts into each range
commanded, the concern is generally an input/
command concern, and not an internal
transmission concern. If ranges are not
completed when using GDS2 to command, then
generally the concern is an internal
transmission concern and not an input/
command concern.
⇒ If noise or vibration concern is noted, follow
Noise and Vibration Analysis in SI using
Chassis Ears and PICO scope in diagnosis.
⇒ If upshifts and downshifts are harsh, soft,
delayed, or slip, follow SI diagnosis for
condition.
Step Five – DTC
If any of the following DTCs are current or reset during
the road test, record on the repair order and follow the
instructions below for that DTC.
• P0796 Transmission Control Solenoid Valve 3
Stuck Off
• P0797 Transmission Control Solenoid Valve 3
Stuck On
• P2723 Transmission Control Solenoid Valve 5
Stuck Off
• P2724 Transmission Control Solenoid Valve 5
Stuck On
If any of the above first group of DTCs are current or
reset on the road test, the transmission must be
removed from the vehicle and inspected for damage to
the clutch plates. If hot spots or other evidence of a
slipping clutch, then follow SI procedure for
replacement of the affected clutch plates and replace
both the solenoid body and valve body.
• P0746 Transmission Control Solenoid Valve 1
Stuck Off
• P0747 Transmission Control Solenoid Valve 1
Stuck On
• P2731 Transmission Control Solenoid Valve 6
Performance
Bulletin No.: 21-NA-169 December, 2021 Page 5
• P2732 Transmission Control Solenoid Valve 6
Stuck Off
• P2733 Transmission Control Solenoid Valve 6
Stuck On
• P2820 Transmission Control Solenoid Valve 9
Stuck Off
• P2821 Transmission Control Solenoid Valve 9
Stuck On
• P18AA Transmission Range Control Valve 1
Position Switch Circuit Stuck On
• P18AB Transmission Range Control Valve 1
Position Switch Circuit Stuck Off
• P18AC Transmission Range Control Valve 2
Position Switch Circuit Stuck On
• P18AD Transmission Range Control Valve 2
Position Switch Circuit Stuck Off
• P18AE Transmission Range Control Enable Valve
Stuck Off
If any of the above second group of DTCs are current or
reset on the road test and the transmission fluid is red,
translucent, and doesn’t have a burnt odor, then only
replace both the solenoid body and valve body. If the
transmission fluid is very dark or black, not translucent,
and has a burnt odor, then in addition to replacing the
solenoid body and valve body, the transmission should
be removed from the vehicle and inspected for damage
to the clutch plates, if found follow SI procedure to
replace them.
• P0741 Torque Converter Clutch (TCC) System
Stuck Off
• P0776 Transmission Control Solenoid Valve 2
Stuck Off
• P0777 Transmission Control Solenoid Valve 2
Stuck On
• P2817 Transmission Control Solenoid Valve 8
Stuck Off
• P2818 Transmission Control Solenoid Valve 8
Stuck On
If any of the above third group of DTCs are current or
reset on the road test and the transmission fluid is red,
translucent, and doesn’t have a burnt odor, then only
replace the solenoid body. If the transmission fluid is
very dark or black, not translucent, and has a burnt
odor, then in addition to replacing the solenoid body,
the transmission should be removed from the vehicle
and inspected for damage to the clutch plates, if found
follow SI procedure to replace them.
• P2714 Transmission Control Solenoid Valve 4
Stuck Off
• P2715 Transmission Control Solenoid Valve 4
Stuck On
• P187D Transmission Park Valve Stuck On
• P187E Transmission Park Valve Stuck Off
If any of the above fourth group of DTCs are current or
reset on the road test and the transmission fluid is red,
translucent, and doesn’t have a burnt odor, then only
replace the valve body. If the transmission fluid is very
dark or black, not translucent, and has a burnt odor,
then in addition to replacing the valve body, the
transmission should be removed from the vehicle and
inspected for damage to the clutch plates. If found,
follow SI procedure to replace them.
• P18A8 Transmission Park Control Solenoid
Actuator Stuck Off
• P18E7 Transmission Park Valve Position Sensor
1 Performance
• P18E8 Transmission Park Valve Position Sensor
2 Performance
• P27EC Transmission Range Control Valve 1
Position Switch Performance
• P27F0 Transmission Range Control Valve 2
Position Switch Performance
Note: If P18A8 is set, then also replace the Park Inhibit
Solenoid Actuator along with the solenoid body and
valve body.
If any of the above fifth group of DTCs are current or
reset on the road test and the transmission fluid is red,
translucent, and doesn’t have a burnt odor, then check
vehicle battery health and state of charge per SI
instructions, also check battery, TCM, and
Transmission ground for voltage loss. If battery and
grounds do not show problem and DTC is current, then
replace both the solenoid body and valve body. If the
transmission fluid is very dark or black, not translucent,
and has a burnt odor, then in addition to replacing the
solenoid body and valve body, the transmission should
be removed from the vehicle and inspected for damage
to the clutch plates. If damage is found, follow SI
procedure to replace the clutch plates.
If there are no current DTCs or they were/are only in
history and are not able to be reproduced, perform the
Transmission Service Fast Learn Procedure in SI and if
no DTCs reset, return the vehicle to the customer.
Symptoms other than listed above should be diagnosed
using SI procedures and repaired as necessary.
Parts Information
No parts are required for this repair.
Page 6 December, 2021 Bulletin No.: 21-NA-169
Warranty Information
For vehicles repaired under the Emission coverage,
use the following labor operation. Reference the
Applicable Warranties section of Investigate Vehicle
History (IVH) for coverage information.
Labor
Operation
Description Labor Time
8486018*
Perform Fluid Level Check
and Evaluate Condition, Oil
Pressure Checks and
Service Fast Learn
1.5 hrs
8463690** Control Valve Body
Replacement
Use
Published
Labor
Operation
Time
8463700
Control Valve Solenoid Body
Replacement
*This is a unique Labor Operation for bulletin use only. This
operation is only used if no other transmission components
are replaced. Can only be used if the vehicle is below 19,
000 km (12,000 miles) on the odometer.
**If valve body and solenoid body are replaced at the same
time, use this Labor Operation.
Note: If transmission is removed from vehicle and internally
inspected for clutch or hardware failure, use the appropriate
valve body or solenoid body Labor Operation for the DTC
and include the clutch or hardware inspection and repair
time as straight time to the labor operation.
Version 3
Modified
Released July 20, 2021
September 28, 2021 – Added the 2022 Model Year, updated information under both
Notes in step 5 under Step Four – Perform Road Test and updated information under Step
5 – DTC.
November 29, 2021 – Added Holden Equinox model, Europe, Australia/New Zealand to
Involved Region or Country section and updated the service publication reference in last
arrow under Information.

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