Diagnostic Tips for DTCs Set at a Low Mileage for 9T65 Transmissions – 2018-2020 Buick Cadillac Chevrolet GMC

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Service Bulletin Bulletin No.: 20-NA-136
Date: November, 2021
INFORMATION
Subject: Diagnostic Tips for DTCs Set at a Low Mileage for 9T65 Transmissions
Attention: The 9T65 Transmission Replacement Pilot Has Ended.
This bulletin only applies to vehicles with less than 19,000 km (12,000 miles) on the
odometer. Vehicles over the mileage refer to SI diagnostics.
Brand: Model:
Model Year: VIN:
Engine: Transmission:
from to from to
Buick Enclave 2018
2022 — — —
M3W
Cadillac
XT5 2020
XT6 2020
Chevrolet
Blazer 2019
M3V
Traverse 2018
GMC Acadia 2020 M3W
Involved Region or Country United States, Canada
Overview
The 9T65 transmission replacement pilot program has
ended as of September 30, 2021 with the end of the
pilot program mandatory transmission assembly
replacement is no longer authorized per this bulletin.
Instead refer to bulletin 20-NA-138 for current
guidelines for replacement of transmission assemblies.
This bulletin is being revised to convey this change and
to provide an enhanced diagnostic and repair strategy
developed through the pilot program teardown and
inspection learnings from returned transmissions.
These strategy changes will keep with the intent of the
replacement pilot program to reduce the number of
days to complete the vehicle repair and reduce the
number of repeat repair visits.
Unlike the replacement pilot program which was only
for the US dealers this diagnostic and repair strategy
can be used by all dealerships servicing vehicles with
9T65 transmissions.
If a customer is commenting on transmission operation
concerns on a 9T65 transmission (RPO M3W and
M3V), follow the steps below to determine repair
strategy.
Please refer to these service publications for
resolutions to customer comments prior to proceeding
with this bulletin.
1. 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
2. 20-NA-060 – High Pitch Noise Heard When
Vehicle is Decelerating
3. PIP5697B – DTC P0747 Setting At Engine
Start-Up When The Transmission Is In Park
4. 21-NA-038 – Humming Noise Heard Coming From
Front End of Vehicle When Driving at Highway
Speeds
5. 21-NA-118 – Vibration Type Noise Heard at
Highway Speeds or with Engine Speed at
1,300-1,500 RPM
Page 2 November, 2021 Bulletin No.: 20-NA-136
6. Torque converter shudder.
• Refer to PIP5608C – TCC Shudder Surge Fish
bite Chuggle
• Refer to latest version of 08-07-30-035 –
Information on Water or Ethylene Glycol in
Transmission Fluid
• Refer to Torque Converter Diagnosis in SI.
• If not resolved, contact Technical Assistance
(TAC). Refer to PIP5621A: GM TAC Support On
Vehicle Automatic Transmission Concerns That
Can Be Duplicated
7. In addition to the complaint, cause, and correction
notes on the repair order, this other information is
required to be noted:
• DTCs found during vehicle diagnosis – include
the DTC, what module it was in and if it was
history or current. Search all modules including
TCM, ECM, BCM, EBCM, IPC, and TRCM.
• Oil level test findings – overfill, under-fill, and
correct level. If over or under, estimate of how
much fluid.
• Oil pressure test results. Record actual
pressure reading taken.
Step One — DTCs
1. 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. Release the brake pedal.
4. 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.
5. Raise the vehicle on a hoist. The vehicle must be
level, with the engine running and the shift lever in
the PARK range.
5619626
6. 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.
7. 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.
8. If fluid level is correct, then check condition of the
fluid.
Bulletin No.: 20-NA-136 November, 2021 Page 3
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8.1. Inspect the fluid color.
– The fluid should be red or dark brown.
– It 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.
8.2. 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, record on the repair order
and it would indicate 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
latest version of Corporate Service Bulletin
Number 08-07-30-035 for testing and, if
confirmed, find the source of the coolant/
water and repair then follow SI document
for “Engine Coolant/Water in Transmission”
for proper transmission repair.
8.3. Inspect for external leaks. Refer to Fluid Leak
Diagnosis.
– If fluid level and condition are ok, proceed to
next step.
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 (1).
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 of 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.
5.1. Apply the brake pedal and ensure the parking
brake is set.
5.2. Move the gear selector through the following
ranges:
⇒ PARK to REVERSE
⇒ REVERSE to NEUTRAL
⇒ NEUTRAL to DRIVE
⇒ DRIVE to REVERSE
⇒ REVERSE to DRIVE
5.3. Pause 2 to 3 seconds in each gear position.
Page 4 November, 2021 Bulletin No.: 20-NA-136
5.4. 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, 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
the delay improves. If it does not and no
DTCs were set, 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.
6.1. 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
6.2. Place the gear selector in the DRIVE position.
6.3. Accelerate the vehicle using a steady throttle
position between 15 and 20 percent. Hold the
throttle steady.
6.4. 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.
6.5. Note any harsh, soft or delayed shifts or
slipping. Note any noise or vibration.
6.6. 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.
6.7. 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:
7.1. Place the gear selector in the DRIVE position.
7.2. Accelerate the vehicle at light throttle (5-10
percent) until 3rd gear is just achieved.
7.3. Quickly increase throttle angle until
commanded gear indicates that a downshift to
2nd gear is commanded.
7.4. Verify that the transmission downshifts within
2 seconds of the throttle movement.
7.5. 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.
7.6. Repeat steps 2 to 4 at higher speed to
achieve 5th gear and then step in to
command a 5th to 4th gear downshift.
Bulletin No.: 20-NA-136 November, 2021 Page 5
7.7. 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.
7.8. Note any harsh, soft or delayed shifts or
slipping. Note any noise or vibration.
8. Coasting Downshifts:
8.1. Place the gear selector in the DRIVE position.
8.2. Accelerate the vehicle to 6th gear with the
TCC applied.
8.3. Release the throttle and apply the brakes.
8.4. Verify that the downshifts occur as
commanded by monitoring gear ratio, which
should change after commanded gear
changes.
8.5. Note any harsh, soft or delayed shifts or
slipping. Note any noise or vibration.
9. Reverse:
9.1. With the vehicle stopped, move the gear
selector to REVERSE.
9.2. Slowly accelerate the vehicle to a 10-15
percent throttle position.
9.3. Verify that there is no noticeable slip, noise or
vibration.
10. Road Test Results:
10.1. 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.
10.2. If noise or vibration concern is noted, follow
Noise and Vibration Analysis in SI using
Chassis Ears and PICO scope in diagnosis.
10.3. 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
• 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
• P187D Transmission Park Valve Stuck On
• P187E Transmission Park Valve Stuck Off
• P18E7 Transmission Park Valve Position Sensor
1 Performance
• P18E8 Transmission Park Valve Position Sensor
2 Performance
• 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
Page 6 November, 2021 Bulletin No.: 20-NA-136
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.
• P0721 Output Speed Sensor Performance
• P0722 Output Speed Sensor Circuit No Signal
• P0723 Output Speed Sensor Circuit Intermittent
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 follow
SI diagnostic for the output speed sensor.
• 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 sixth 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 found, follow SI procedure to
replace them.
If any of the DTCs are not reproduced during testing
and only seen in History, then perform the Transmission
Service Fast Learn Procedure. If no DTCs, reset and
return the vehicle to the customer.
Symptoms other than listed above should be diagnosed
using SI procedures and repaired as necessary.
Warranty Information
For vehicles repaired under the Powertrain coverage,
use the following labor operation. Reference the
Applicable Warranties section of Investigate Vehicle
History (IVH) for coverage information.
Labor
Operation
Description Labor Time
8481048*
Perform Fluid Level and 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 transmission assembly is not
replaced.
**Because the transmission is not to be disassembled for
this bulletin, the 1.5 hours add time for “Disassemble,
Inspect, Determine Repair and Re-assemble for Core
Return” should not be claimed.
***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
appropriate control valve body or control solenoid body
labor operation for the DTC and include the clutch or
hardware inspection and repair time as straight time to
the labor operation.
Bulletin No.: 20-NA-136 November, 2021 Page 7
Version 8
Modified
Released June 26, 2020
Revised August 18, 2020 – Added the Warranty Information section.
Revised September 25, 2020 – Added the 2021 Model Year.
Revised May 26, 2021 – Update information in the Overview section, Step One-DTC
section, Step Five DTC section and the Warranty Information section.
Revised July 13, 2021 – Update information in the Overview section after Step 3 to
Extend Pilot Program.
Revised August 05, 2021 – Added the 2022 Model Year.
Revised October 01,2021 – Add Attention statement, Update Overview and Warranty
Information section.
Revised November 23, 2021 – Updated #5 under Overview.

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