21-NA-181

Bulletin No.:
Service Bulletin
Date:
21-NA-181
August, 2023
INFORMATION
Subject:
Information on 9TH Gear Operation
Model Year:
Brand:
Buick
Cadillac
Model:
GMC
to
from
to
Engine:
Transmission:
(9-Speed
Automatic)
Encore GX
2020
L3T
M3F
Envision
2021
LSY
M3G, M3H
XT4
2019
LSY
M3H
LSY
M3G
LSY
M3T
XT5
XT6
Chevrolet
from
VIN:
2020
2024
—
—
Blazer
2020
Trailblazer
2021
L3T
M3F
Acadia
2020
LSY
M3G
Terrain
2018
LYX, LSD
M3U
Involved Region or Country
North America, Europe, Middle East, Israel, Cadillac Korea (South Korea), China
Condition
Some customers may comment that the transmission doesn't shift into 9th gear or
maintain 9th gear operation to customer expectations.
Information
The GM 9-speed transmission does use all 9 gears when most efficient to do so. The
vehicle's control system senses the operating conditions and chooses the correct gear to
deliver optimum performance and fuel economy. The control calibration is also tailored for
each vehicle application and engine type. On the highway for example, optimal fuel
economy may be achieved in 8th gear rather than 9th gear depending on a number of
factors including vehicle speed, engine load, and throttle input. 9th gear is engaged when
appropriate.
Note: Replacing transmission components or complete assemblies will not change the
condition. To ensure 9th gear is operating, verify 9th gear is not being commanded on a
test drive. Then with GDS2, manually command 9th gear. If achieved, the vehicle system
is operating correctly.
Copyright 2023 General Motors LLC. All Rights Reserved.
Page 2
August, 2023
Bulletin No.: 21-NA-181
Important: Service agents must comply with all
International, Federal, State, Provincial, and/or
Local laws applicable to the activities it performs
under this bulletin, including but not limited to
handling, deploying, preparing, classifying,
packaging, marking, labeling, and shipping
dangerous goods. In the event of a conflict between
the procedures set forth in this bulletin and the
laws that apply to your dealership, you must follow
those applicable laws.
Parts Information
No parts are required for this repair.
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
8486038*
Description
Labor Time
Confirm 9TH Gear
Operation
0.3 hr
*This is a unique Labor Operation for bulletin use only.
Version
5
Modified
Released August 12, 2021
Revised December 21, 2021 – Added RPO M3H to Envision.
Revised April 08, 2022 - Add 2022 Model Year to Terrain.
Revised August 29, 2022 - Add 2023 Model Year.
Revised August 08, 2023 - Add 2024 Model Year and Added Engine RPO LSD to Terrain.
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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