21-NA-181 Service Bulletin/Repair Instructions

Service Bulletin
Bulletin No.:
21-NA-181
Date:
April, 2022
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
2022
—
—
Blazer
2020
Trailblazer
2021
L3T
M3F
Acadia
2020
LSY
M3G
Terrain
2018
LYX
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 actually 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.
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.
Copyright 2022 General Motors LLC. All Rights Reserved.
Labor

Operation

8486038*
Description
Labor Time
Confirm 9TH Gear

Operation
0.3 hr
*This is a unique Labor Operation for bulletin use only.
Page 2
April, 2022
Bulletin No.: 21-NA-181
Version
3
Modified
Released August 12, 2021

Revised December 21, 2021 – Added RPO M3H to Envision.

Revised April 08, 2022 - Add 2022 Model Year 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.
WE SUPPORT VOLUNTARY

TECHNICIAN

CERTIFICATION

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