23-NA-135

Bulletin No.:
Service Bulletin
Date:
23-NA-135
March, 2024
INFORMATION
Subject:
Information on Oil Level Control Changes and Compatibility on 2023-2024 9-Speed
Transmissions
Note:
This document is to be used to identify the correct part to match the correct year for
your application. Vehicles involved does not change.
Brand:
Model:
Model Year:
from
to
Enclave
Buick
Cadillac
Encore GX
Engine:
Transmission:
2023
2024
M3F
Envision
M3H
XT4
M3H
XT5
2023
2024
Trailblazer
2023
Traverse
Acadia
Terrain
M3G, M3W
M3G, M3W
Blazer
GMC
to
M3W
XT6
Chevrolet
VIN:
from
2023
2024
M3T, M3V
M3F
2023
M3V
2023
M3G, M3W
2024
M3U
Involved Region or Country
North America, Europe, Kazakhstan, Uzbekistan, Russia, Middle East, Israel, Palestine,
Bolivia (West), Chile (West), Colombia (West), Japan, Cadillac Korea (South Korea), GM
Korea Company, China - SGM, Taiwan, Other Africa
Information
The purpose of this bulletin is to inform the Service Department Personnel about an
update to the GM 9-speed transmission automatic transmission fluid Oil Level Control
system (OLC). The purpose of the system is to store fluid in the side cover as the
transmission warms up.
The system used from the beginning of the 9-speed transmission thru 2023 consists of:
• standpipe with a thermal door
• on/off solenoid
• valve
The changes to the system starting with 2024 MY and some 2023 models with the RPO
BCE are described below.
Copyright 2024 General Motors LLC. All Rights Reserved.
Page 2
March, 2024
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.
Additional Information
Note: With OLC (w/OLC) means original design of
OLC system. Without OLC (w/o OLC) means the new
design of the OLC system.
6396977
• 1) To only be used in model year 2022 and prior.
• 2) Can be used in any model year.
The previous a/trans fluid level control valve on the
standpipe (item #21) had a small thermal door. The new
style can be recognized by the larger thermal door on
the standpipe. The larger thermal door is necessary for
the removal of the OLC components.
Bulletin No.: 23-NA-135
Bulletin No.: 23-NA-135
March, 2024
Page 3
6396979
•
•
1) For use in model year 2023 and prior (w/OLC).
2) For use in model year 2024 and forward (w/
o OLC).
The valve body will eliminate the a/trans fluid valve
(item #437 and #436).
6397367
•
•
1) For use in model year 2023 and prior (w/OLC).
2) For use in model year 2024 and forward (w/
o OLC).
Page 4
March, 2024
Bulletin No.: 23-NA-135
The valve body to transmission case spacer plate is
covering over the port (item #456).
6397498
•
•
1) For use in model year 2023 and prior (w/OLC).
2) For use in model year 2024 and forward (w/
o OLC).
The solenoid body will eliminate the a/trans fluid control
solenoid (item #403).
6397499
•
•
1) For use in model year 2023 and prior (w/OLC).
2) For use in model year 2024 and forward (w/
o OLC).
Bulletin No.: 23-NA-135
March, 2024
Page 5
The a/trans wiring harness will eliminate the wire for the
a/trans fluid control solenoid (item #31).
6397504
Note: Both valve body covers are Interchangeable.
• 1) Old Design
• 2) New Design
The previous style valve body cover did not have a plug
hole in it. The new style cover will have a plug. This
new plug should not be removed as it is used by the
assembly plant only.
When servicing these transmission components, the
technician must use the parts that are specified in this
TSB for the model year being repaired. There is a
possibility the components for a 2024 vehicle may be
the old style. This is not a concern or a mis-build, this is
to facilitate the manufacturing process. This is possible
because the 2024 and 2023 RPO BCE transmission
calibration ignores those component inputs.
Transmission quality concerns (up to and including
transmission failure) can occur if transmissions are not
serviced according to instructions.
Version
3
Modified
Released July 31, 2023
Revised August 16, 2023 - Added 2023 to 2024 to Model Year, Update the Information
and Additional Information sections.
Revised March 19, 2024 - Added a Note Statement under the Subject.
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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