Bulletin No.:

Service Bulletin

Date:

18-NA-114
February, 2020

TECHNICAL
Subject:

Service All Wheel Drive (AWD)/Service Stability Messages Displayed on Driver
Information Center (DIC), Erratic Speedometer Readings, Malfunction Indicator Lamp
(MIL) Illuminated - DTC P0641, U0073, U0100, U0101, U0121, U0131 and/or U0136 Set

Brand:

Model:

Chevrolet

Trax

Model Year:

VIN:

from

to

2018

2020

Involved Region or Country

from

to

Engine:

Transmission:

1.4L (LUV)

North America and Israel
Note: Not all of the effects or driver notifications listed have been experienced. However,
the different effects and driver notifications may be caused by one of the wires in the
wiring harness being chafed or cut. Components on different lines in the list below are in
different circuits. Due to the cause of the condition, and the positions of the wires in the
harness, it is unlikely that more than one circuit and/or fuse will be affected by the
condition.

Condition

Cause

Copyright 2020 General Motors LLC. All Rights Reserved.

Some customers may comment on one or more of the following conditions:
• MIL is illuminated
• Service AWD message displayed on DIC
• Service Stability message displayed on DIC
• Erratic speedometer readings
The technician may find one or more of the following DTCs set:
• P0641: 5V Reference 1 Circuit set in the Engine Control Module (ECM)
• U0073: Control Module Communication Bus A Offset in the ECM or TCM
• U0100: Multiple state of health messages, set in the ECM or TCM
• U0101: Lost Communication with Transmission Control Module
• U0121: Lost Communication with Electronic Brake Control Module
• U0131: Lost Communication with Power Steering Control Module
• U0136: Lost Communication with Differential Control Module - Rear
Note: This is a multi-wire bundled harness and, depending on which wire is damaged,
can set a variety of DTCs.
This condition may be caused by the engine harness chaffing against the
G100 Ground stud.

Page 2

February, 2020

Bulletin No.: 18-NA-114

Correction

5040432

If the above condition has been validated, inspection of the engine wiring harness must
be done.
1. With a suitable light, inspect the wiring harness point of contact at the
G100 ground stud.

⇒ For stud location, refer to Document ID: 4708510 in SI.
2. Repair the harness as needed.

⇒ Refer to Wire to Wire Repair in SI.

Bulletin No.: 18-NA-114

February, 2020

Page 3

5040564

3. Using Woven Polyester Electrical Tape (PET), tape all the contact points of the
engine harness ensuring that the tape is applied in a double layer.
4. Reposition the engine harness so that it cannot contact the ground stud.

⇒ If required, replace the blown fuse in regards to repair performed on the
engine harness.

Parts Information
No parts are required for this repair.

Warranty Information
For vehicles repaired under warranty, use:
Labor
Operation

Description

Labor Time

5430902

Wire-to-Wire Repair

Use
Published
Labor
Operation
Time

Page 4

February, 2020

Bulletin No.: 18-NA-114

Version

5

Modified

Released April 12, 2018
May 4, 2018 – Changed the Engine RPO and added Additional Keywords.
June 12, 2018 – Updated the Subject and Condition sections to add additional DTCs and
conditions.
March 28, 2019 – Added the 2019 Model Year.
February 3, 2020 – Added the 2020 Model Year.

Additional Keywords: 5V ref, B111B, Turbo boost
sensor

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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