16-NA-019 Service Bulletin/Repair Instructions

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

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