23-NA-162

Bulletin No.:
Service Bulletin
Date:
23-NA-162
December, 2023
INFORMATION
Subject:
Information on Service Rear Axle Message Displayed on Driver Information Center
(DIC) – DTC C039F, C0407, C0408, and/or C0393 Set
Brand:
Buick
Cadillac
Model:
Model Year:
VIN:
from
to
LaCrosse
2010
2017
Regal
2013
2019
SRX
2010
2016
XTS
2013
2019
from
to
—
—
Engine:
Transmission:
3.6L
(LFX, LF3)
2.0L
Turbo (LTG)
—
Involved Region or Country
North America
Addition RPO
F46: CHASSIS DRIVE LINE-ALL WHEEL DRIVE (AWD), FULL TIME
G96: AXLE POSITRACTION-LIMITED SLIP, ELECTRONIC
Condition
Some customers may comment on a Service Rear Axle Message displayed on the Driver
information Center (DIC).
Technicians may find one or more of the following DTCs:
• C039F
• C0407
• C0408
• C0393
Information
Current diagnostic procedures have been updated to better assist in diagnosing the rear
differential mechanical & electrical components. Previous documentation was not clear,
which led to mis-diagnosis for module replacement.
Diagnostic procedures in Service Information have been updated to address
misdiagnosis resulting in replacing the Rear Differential Control Module (RDCM) or
Module Kit.
Perform new published diagnostics (DTCs) in Service Information:
• If a SPAC case was issued and new information corrected the vehicle without
replacing the module, please cancel Module Kit SPAC Case.
• If the new diagnostic leads to replacement of the Diff Clutch Valve, a new Diff Clutch
Valve Kit (P/N 19435486) is now available individually (Diff Clutch Valve was previous
only available as part of Module kit or diff clutch assembly).
Copyright 2023 General Motors LLC. All Rights Reserved.
Page 2
December, 2023
Bulletin No.: 23-NA-162
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.
Version
1
Modified
Released November 30, 2023
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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