16-NA-019

Service Bulletin
Bulletin No.:
16-NA-019
Date:
May, 2022
INFORMATION
Subject:
Information on Transmission Adaptive Functions and Correcting Low Mileage Harsh
Shifts, Slips, or Flares
Model Year:
Brand:
Cadillac
Chevrolet
GMC
Model:
from
to
VIN:
from
to
Engine:
Transmission:
(8-Speed
Automatic)
ATS
2016
2019
M5N, M5U
CTS
2016
2019
M5N, M5U
CT6
2016
2018
M5N, M5X
CT4
2020
2022
M5N
Escalade
2015
2017
M5U
Camaro
2016
2022
M5T, M5U
Corvette
2015
2019
M5U
Colorado
(VIN S, VIN T)
2017
2022
M5T
Express
2017
2022
M5U, MQD
Silverado
2015
2018
M5U, M5X
Silverado 1500
(New Model)
2019
2019
MQE
MQE
Silverado
2020
2021
Silverado 1500 (LTD, RPO J21,
12th VIN Digit = 4
or less)
2022
2022
Silverado 1500 (RPO J22, 12th
VIN Digit = 5 or
greater)
2022
M5X, MQE
—
2022
—
All
M5X, MQE
Canyon
2017
2022
M5T
Sierra
2015
2018
M5U, M5X
Sierra 1500
(New Model)
2019
2019
MQE
Sierra
2020
2021
MQE
Sierra 1500 (LIMITED RPO
J21, 12th VIN Digit
= 4 or less)
2022
2022
M5X, MQE
Sierra 1500 - (RPO
J22, 12th VIN Digit
= 5 or greater)
2022
2022
M5X, MQE
Savana
2017
2022
M5U, MQD
Yukon
2015
2017
M5U
Copyright 2022 General Motors LLC. All Rights Reserved.
Page 2
May, 2022
Bulletin No.: 16-NA-019
Involved Region or Country
North America, China, Middle East, Japan, Europe, Korea, Brazil, Thailand, Egypt, Israel,
Guatemala, Peru, Ecuador, Argentina, India, Colombia, Indonesia, Vietnam, Uzbekistan,
South Africa, Venezuela, Philippines, Albania, Kuwait
Condition
Some customers may comment on low mileage vehicles with an automatic transmission
that the shifting may feel too firm (harsh), slips, or flares. Customers should be advised
that the transmission makes use of an adaptive function that will help to refine the shift
feel while driving and improve shift quality.
Note: Low mileage would be considered vehicles that have approximately 8050 km
(5000 mi) or less or on vehicles that have had a valve body, clutch repair or transmission
replacement in the last approximate 8050 km (5000 mi) or less.
Correction
Important: Using Tis2Web, please check the ECM/
TCM Software/Calibrations against what is currently in
the vehicle and if the description of the update is
relevant to the customer concern, please perform the
update prior to proceeding with the learns below. By
completing the software/calibration update, the clutch
adapts will clear and thus a Service Fast Learn (SFL)
followed by Adaptive Learning may be needed to
further learn specific clutches if shift concern exists.
The following should be used to determine what steps
should be followed within this document. The 8-Speed
transmission utilizes a total of 5 clutches to obtain all
the ratios. Utilize the chart within this document to
determine which clutch may require additional adaptive
learning.
• If a valve body replacement, clutch repair/overhaul
or transmission replacement was required, reset
the adapts using Service Fast Learn. Evaluate the
shifts and further learn pressures and volumes if
required using the procedure below.
• If a customer has a specific shift concern, the
Service Fast Learn (SFL) should be skipped.
Complete the Adaptive Learn procedure to further
learn pressures and volumes for the specific shift
concern.
Note: The Adaptive Learn procedure should be used
on vehicles that have approximately 8050 km (5000 mi)
or less or on vehicles that have had a valve body, clutch
repair or transmission replacement in the last
approximate 8050 km (5000 mi) or less. Performing the
Adapt procedure on high mileage vehicles may improve
shift quality for a limited amount of time but the vehicle
will most likely return with the same symptoms.
Transmission Adaptive Functions
The Hydra-Matic® 8-Speed RWD transmission utilizes
a line pressure and volume control system during
upshifts to compensate for new transmission build
variation as well as the normal wear of transmission
components. The variation from new and normal wear
of the apply components within the transmission over
time can cause shift time (the time required to apply a
clutch) to be longer or shorter than desired.
In order to compensate for these changes, the
transmission control module (TCM) adjusts the
pressure commands to the various pressure control
(PC) solenoids to maintain the originally calibrated shift
timing. The automatic adjusting process is referred to
as “adaptive learning” and it is used to ensure
consistent shift feel plus increase transmission
durability.
The TCM monitors the A/T input speed sensor (ISS)
and the A/T output speed sensor (OSS) during
commanded shifts to determine if a shift is occurring
too fast (harsh) or too slow (soft) and adjusts the
corresponding PC solenoid signal to maintain the set
shift feel. The purpose of the adapt function is to
automatically compensate the shift quality for the
various vehicle shift control systems. The adapt
function is a continuous process that will help to
maintain optimal shift quality throughout the life of the
vehicle.
How to Adapt Your Transmission
Transmission adapts can be reset and relearned on
most vehicles through GDS2 by using the Transmission
Service Fast Learn procedure. This procedure is
completed in the service stall and no vehicle driving is
required.
To complete the Transmission Service Fast Learn
procedure, enter GDS2 Diagnosis and navigate to:
• Module diagnostics
• Transmission Control Module
• Configuration / Reset Function
• Transmission Service Fast Learn
Transmission Service Fast Learn is the recommended
method to reset and relearn adapts. This procedure is
available on all 2015-2021 MY Trucks, Cars and SUVs
with 8L45 and 8L90 Automatic Transmissions (RPOs:
M5U, M5T, M5N, M5X, MQD, MQE).
When the Service Fast Learn is complete, perform a
test drive and note any soft or harsh shifts.
To improve these complaint shifts further, locate the
clutches that need to be learned in the table below, and
perform the required learning procedure for each clutch
listed in the table. Execute the steps below with the
vehicle warmed up on a smooth level road. The driver
may observe a brief pulse behavior or firm shift feel
while the transmission is optimizing the clutch learn
characteristics.
Note: The transmission fluid temperature must be
between 35°C (95°F) and 95°C (203°F). Drive the
vehicle under normal conditions until this temperature
range is achieved. If the temperature is outside of this
range, the clutches will not be learned.
Bulletin No.: 16-NA-019
To Correct The
Shift Feel
May, 2022
Learn These Clutches
Page 3
2. Volume Learns:
• Complete 15 light throttle 6-7 upshifts at
approximately 15% throttle to further learn C1.
Applying
Clutch
Releasing
Clutch
1–2
C4
C3
To Learn C2 (For 6-5 Shift)
2–3
C3
C1
3–4
C5
C3
4–5
C3
C4
1. Pressure Learns:
Note: It is recommended to utilize a road with a speed
limit 64-72 km/h (40-45 mph) for this procedure.
5–6
C4
C2
6–7
C1
C4
7–8
C4
C3
3–1
C1
C4
2–1
C3
C4
N-D
C3 – Perform garage shift adaptive
learning
N-R
C5 – Perform garage shift adaptive
learning
Power Downshifts
Just perform the shifts and they will
adapt
Note: Ensure Service Bulletin #16-NA-411 or
#16-NA-412 has been completed on the 2015 -2016
Silverado, Sierra, Yukon and Escalade models before
performing this procedure.
Note: For the 2015 Corvette, use the latest version of
Service Bulletin #14-07-30-001.
Note: The following adaptive learning procedure
was developed to further learn clutch pressures
and volumes required for specific shifts. To
expedite the learning process, it is recommended
to utilize a road with minimal traffic volume that has
as smooth and level surface as possible.
Note: Within GDS2, a Transmission Service Fast
Learn Data page has been created to aid in performing
adaptive learn by showing throttle percentage, engine
speed, transmission fluid temperature, and gear
command.
Note: 2018-2022 Model Year vehicles show the clutch
learn status within GDS2. A Transmission Service Fast
Learn Data page has been created to aid in performing
adaptive learn by showing throttle percentage, engine
speed, transmission fluid temperature, and gear
command.
To Learn C1 (For 6-7 or 3-1 Shift)
1. Pressure Learns:
Note: It is recommended to utilize a road with a speed
limit between of 48-72 km/h (30-45 mph) for this
procedure.
• Shift the transmission into 6th gear with the
PRNDM in the M position. Obtain an engine
speed between 1000 and 1600 engine rpm.
Maintain this condition for a total of about 8 km
(5 mi). Cruise control may be used and has
been found to result in faster learning of the
clutch values.
• Perform 10 normal mode 6-5 coast down shifts
(zero/light brake) to learn the C2 Return Spring
pressure.
2. Volume Learns:
• Shift the transmission into 8th gear with the
PRNDM in the M position. Obtain an engine
speed between 1000 and 1750 rpm. Maintain
this condition for a total of about 8 km (5 mi).
Cruise control may be used and has been found
to result in faster learning of the clutch values.
To Learn C3 (For 2-3, 4-5, or N-D Shift)
Important: Application Specific Silverado & Sierra
e-Assist (RPO M5X) Trucks: To enable Adaptive
Learn on 8-7 Coast downs, a power on (~15% throttle
through the upshift) 7-8 upshift must be performed prior
to each downshift. This action enables torque converter
clutch (TCC) controlled slip on downshift to occur vs.
TCC unlocked, which occurs on normal downshifts and
disables Adaptive Learn. As a supplement, if the
previous procedure is unsuccessful using GDS TCC
Control Functions, TCC can be left enabled during 8-7
Coast downs to aid in learning C3 pressure.
1. Pressure Learns:
• Perform 10 normal mode 8-7 coast down shifts
(zero/light brake) to learn the C3 Return Spring.
2. Volume Learns:
• Complete 15 light throttle 2-3 upshifts at
approximately 15% throttle to further learn C3.
To Learn C4 (For 1-2, 5-6, or 7-8 Shift)
1. Pressure Learns:
Note: It is recommended to utilize a road with a speed
limit between of 64-72 km/h (40-45 mph) for this
procedure.
• Shift the transmission into 7th gear with the
PRNDM in the M position. Obtain an engine
speed between 1000 and 1750 rpm. Maintain
this condition for a total of about 8 km (5 mi).
Cruise control may be used and has been found
to result in faster learning of the clutch values.
Important: Application Specific Express & Savana
Vans Pressure Learns: Perform 10 normal mode 7-6
coast down shifts (zero/light brake) to learn the C4
Return Spring.
2. Volume Learns:
• Complete 15 light throttle 1-2 upshifts at
approximately 15% throttle to further learn C4.
Page 4
May, 2022
To Learn C5 (For 3-4 or N-R Shift)
1. Pressure Learns:
Note: It is recommended to utilize a road within a
Business Park or similar area, where it is safe to drive
at very slow speeds of approximately 8-40 km/h
(5-25 mph).
• Shift the transmission into 3rd gear with the
PRNDM in the M position. Start a very slow
acceleration, starting at about 1000 rpm.
Maintain the slow acceleration until you reach
about 2500 rpm. Once you reach 2500 rpm,
slow back down to 1000 rpm and repeat the
slow acceleration up to 2500 rpm. Repeat this
10 times.
2. Volume Learns:
• Complete 15 light throttle 3-4 upshifts at
approximately 15% throttle to further learn C5.
Power Downshift Adaptive Learning
Starting with the vehicle operation in 8th gear, slowly
apply pressure to the accelerator pedal until downshift
occurs. Repeat as necessary in each gear (8, 7, 6, 5, 4,
3 and 2).
Note: This procedure will learn the off-going clutch
adapts for desired power downshift control.
Bulletin No.: 16-NA-019
Garage Shift Adaptive Learning (For N-D or N-R
Shift)
1. After above clutches are learned C3 –Drive and C5
– Reverse. With the vehicle at a stop, hold foot on
brake pedal and move the shifter from Neutral to
Drive and release the brake once in gear allowing
the vehicle to roll 5-10 feet or Neutral to Reverse
and release the brake once in gear allowing the
vehicle to roll 5-10 feet. Repeat as necessary until
desired shift quality is achieved.
Note: This procedure will learn the C13567 (C3-Drive)
and C45678R (C5 – Reverse) oncoming clutch adapts.
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
8480318*
Transmission Service Fast
Learn
Use Actual
Clock Time
*This is a unique Labor Operation for bulletin use only.
Version
8
Modified
Released January 25, 2016
August 19, 2016 – Added the 2017 Model Year and updated information.
November 13, 2019 – Added the 2018 Model Year and a Warranty statement.
September 02, 2020 – Removed Buick from Models table, added the 2015 and 20192021 Model Years, added RPO MQE, updated the Involved Region or Country section,
updated the two bullet items under Correction, added a Note to the Condition and
Correction sections and updated the Notes just below the Shift/Clutch table.
November 16, 2020 – Added RPO MQD and updated Description of Labor Operation.
December 01, 2020 – Changed Labor Operation Description back to previous
Description.
July 20, 2021 – Changed Models from GM Passenger Cars and Trucks to specific Models
and Years.
May 06, 2022 – Added the 2022 Model Year to certain vehicles and updated the Involved
Region or Country section.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.
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