23-NA-149

Bulletin No.:
Service Bulletin
Date:
23-NA-149
February, 2024
TECHNICAL
Subject:
Brand:
Cadillac
Chevrolet
GMC
Check Trailer Wiring Message Displayed, Trailer Brake Disabled, and/or DTC C1114
Stored when Pulling Trailer with a Battery Generator or Solar Charger
Model:
Model Year:
from
to
Escalade Models
2023
2023
Silverado 2500HD/
3500HD
2024
2024
Silverado EV
2024
2024
Colorado
2023
2023
Silverado 4500/5500
2023
2023
Suburban
2023
2023
Tahoe
2023
2023
Sierra 2500HD/
3500HD
2024
2024
HUMMER EV
2024
2024
HUMMER EV SUV
2024
2024
Canyon
2023
2023
Yukon Models
2023
2023
VIN:
from
to
–
–
Engine:
Transmission:
All
All
Involved Region or Country
North America, Middle East, Israel
Condition
Some customers may comment on a check trailer wiring message displayed, trailer brake
disabled when pulling trailer with a battery generator or solar charger.
During Diagnosis a technician may find DTC C1114 set/stored.
Cause
The issue may be caused by the solar panel battery charger or generator on the
customer's trailer. If the trailer battery becomes fully charged and has a higher charge
then the vehicle battery, it can back feed into the trailer brake power module and cause it
to shut down.
Additional information for some ICE vehicles and EVs:
• For ICE (internal combustion engine) vehicles - During vehicle start up or stop/start
event
• For EV's (electric vehicles) – When vehicle placed in propulsion (PROP)
If the trailer battery has a higher state of charge than the vehicle battery, it can also cause
this condition until the vehicle's charging system brings the vehicle battery up to a higher
state of charge. The message should go away and the trailer brakes will work as normal.
Correction
Replace the trailer brake module with updated part.
Copyright 2024 General Motors LLC. All Rights Reserved.
Page 2
February, 2024
Bulletin No.: 23-NA-149
Service Procedure
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.
If you encounter a vehicle with the above concern,
replace the trailer brake module. Refer to Trailer Brake
Control Module Replacement in Si.
Parts Information
Causal
Part
Description
Part
Number
Vehicles
X
Trailer Brake
Control Module
23306694
Silverado
HD/
Sierra HD
Colorado/
Canyon
HUMMER
EV
Silverado EV
84857588
Suburban
Tahoe
Escalade
Yukon
23337305
4500/5500
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
2210300
Trailer Brake Control Module Replacement
Use Published Labor
Operation Time
Version
3
Modified
Released September 01, 2023
Revised September 15, 2023 – Added Suburban, Tahoe, Yukon, Escalade Models and
Part #.
Revised February 15, 2024 – Updated Subject and Condition.
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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