Information on 9TH Gear Operation – 2018-2023 Buick Cadillac Chevrolet GMC

NHTSA ID Number: 10219391

Manufacturer Communication Number: 21-NA-181


This service bulletin provides 9th gear operation information to respond to customers that may comment on transmission shift operation.



Some customers may comment that the transmission doesn’t shift into 9th gear or
maintain 9th gear operation to customer expectations.



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.


32 Affected Products


CADILLAC XT4 2019-2022
CADILLAC XT5 2020-2023
CADILLAC XT6 2020-2023
GMC ACADIA 2020-2023
GMC TERRAIN 2018-2022


1 Associated Document

Manufacturer Communications

Bulletin No.: 21-NA-181
Date: September, 2022

MC-10219391-0001.pdf 70.727KB




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Last update on 2023-03-19 / Affiliate links / Images from Amazon Product Advertising API

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