21-NA-155

Service Bulletin
Bulletin No.:
21-NA-155
Date:
June, 2022
INFORMATION
Subject:
Information on Check Trailer Wiring Message and/or Service Trailer Brake Displayed
on Driver Information Center (DIC) - DTC C1114 Set
Brand:
Model:
Cadillac
to
Escalade Models
2021
2022
Silverado 1500
(New Model)
2019
2019
Silverado 1500
2020
2021
2022
2022
2020
2022
2021
2022
Sierra 1500
(New Model)
2019
2019
Sierra 1500
2020
2021
2022
2022
Sierra
2500HD/3500HD
2020
2022
Yukon Models
2021
2022
Silverado 1500 - LTD
(RPO J21,
VIN Digit 5 = W / Y)
Chevrolet
Silverado 1500 - New
(RPO J22,
VIN Digit 5 = A / D)
Silverado 2500HD/
3500HD
Suburban
Tahoe
GMC
Model Year:
from
Sierra 1500 - Limited
(RPO J21,
VIN Digit 5 = 8 / 9)
Sierra 1500 - New
(RPO J22,
VIN Digit 5 = H / U)
VIN:
from
to
Engine:
Transmission:
Involved Region or Country
North America, Middle East, Chile (West), Thailand (ASEAN), Paraguay
Additional Options (RPOs)
JL1 (CONTROL-INTEGRATED TRAILER BRAKE)
Condition
Some customers may comment on one or more of the following messages displayed on
the DIC:
• Check Trailer Wiring
• Service Trailer Brake
Some technicians may find DTC C1114 set on vehicles equipped with an Integrated
Trailer Brake Controller.
Copyright 2022 General Motors LLC. All Rights Reserved.
Page 2
June, 2022
Bulletin No.: 21-NA-155
Note: The below two possible causes can also affect a truck equipped with an
aftermarket trailer brake controller
Cause
This condition may be caused by a poor connection at the 7-way trailer connector at the
vehicle and/or trailer side of the connector.
– Trailer Side Connector (Plug) - There are several manufacturers of 7-way (trailer side)
connectors and many do not comply with the SAE standard specifications. Some
7-way (trailer side) connector plugs may not properly engage the truck's 7-way
connector socket and cause open circuits. Since the Trailer Brake Control Module is
always monitoring the vehicle and trailer circuits/components, a poor connection at the
7-way connector can cause a Check Trailer Wiring message on the DIC. This may also
cause deformation and excessive wear of the terminals on the truck's 7-way connector
socket. Over time, this will lead to poor terminal tension between the 7-way (trailer
side) connector plug and the truck's 7-way connector socket.
7-Way Trailer Connector:
– The 7-Way Trailer Side Connector (Plug) - Engineering has recommended the use of
Pollak Heavy Duty 7-Way (Trailer Side) Connector Plugs. Pollak is the OEM
manufacturer of the truck's 7-way connector socket; and by using a Pollak Heavy Duty
7-Way (Trailer Side) Connector Plug, this will ensure proper fit when the two
connectors are mated. Pollak's website is: www.pollakaftermarket.com. Once at the
home page select "Connectors" then "Heavy Duty 7-Way Plugs and Accessories" and
then " RV Connectors Heavy Duty & Adaptors" (example 12-706, 12-702).
Note: If the truck's 7-way connector socket terminals are deformed or have excessive
wear, it will be necessary to replace the truck side connector, see info below, along with
the trailer's 7-way connector plug to a Pollak HD.
Information
• Truck Side Connector (Socket) - If the truck's 7-way trailer connector socket terminals
are deformed, have excessive wear, door/cover not holding trailer connector plug
securely, etc. it will be necessary to replace the truck side trailer connector socket with
updated GM part number 84056018.
Trailer Side Customer Recommendation:
1. Inspect and clean the ground wire (normally white wire) connection on the trailer
side of the 7-pin connector.
2. Make sure that the wires inside the trailer side connector are clean and securely
fastened.
3. If an electrical junction box exists on the trailer, make sure the wires inside the
junction box are clean and securely fastened.
4. Inspect Trailer Grounds for potential issues.
Note: Trailer System issues should not be covered under the GM Bumper-to-bumper
warranty.
Customer Trailer Recommendation:
Refer to bulletin : Information On Common Customer Trailer Side Faults to print the
procedure that can be used to help the customer understand any trailer related issues.
Note: Trailer side system issues should not be covered under the GM
Bumper-to-bumper warranty.
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.
The Following Failures are the Result of
Trailer Side Connection Issues - Non
Warranty Issue
⇒ When diagnosing trailer message issues without
the trailer present, please refer to Document ID:
5627183: PIT5509G: Diagnostic Tip - Check and/or
Service Trailer Brake System message DTC C1114
Bulletin No.: 21-NA-155
June, 2022
Page 3
The Following failures are the result of trailer side
connection issues:
5867995
5867917
1. Short on trailer side damaged the terminal – Trailer
side connector is loose/worn – Non-Warranty
Issue.
5867994
2. The blue/green is expected, and this small amount
of corrosion does not impact function of connector
– Non-Warranty Issue.
3. Trailer side connector is damaged/deformed
causing removal of protective plating. This is the
result of the trailer side connector is moving or
bouncing when connected (excessively worn
connector) – Non-Warranty Issue.
5867997
4. Trailer side harness retention tab has been broken
off cover which is the result of customer pulling
away from trailer without releasing the trailer
harness – Non-Warranty Issue.
Page 4
June, 2022
The Following Failures are the Result of
Vehicle Side Connection Issues Subject to Terms of Warranty
5867998
1. Sealant from part on terminals, would cause
intermittent connection issues connecting to trailer
– Subject to terms of warranty.
5868000
2. Terminal is pushed out – Subject to terms of
warranty.
Parts Information
Causal
Part
Description
N/A
84056018
Part
Number
Truck 7-way
Trailer
Connector
Socket
Qty
1
Bulletin No.: 21-NA-155
Bulletin No.: 21-NA-155
June, 2022
Page 5
Warranty Information
For trailer related issues: No warranty labor operation is
provided for concerns related to the trailer.
For Truck 7-Way Connector Replacement use: For
vehicles repaired under the Bumper-to-Bumper
coverage (Canada Base Warranty coverage), use the
following labor operation. Reference the Applicable
Warranties section of Investigate Vehicle History (IVH)
for coverage information.
Labor Operation
Description
Labor Time
5486198*
Tow Vehicle Electrical Receptacle Diagnostic
0.3 hr
Add
Tow Vehicle Electrical Receptacle Replacement
0.2 hr
*This is a unique Labor Operation for Bulletin use only.
Version
2
Modified
Released September 21, 2021
Revised June 14, 2022 - Added 2022 to Model Year and Updated Information section.
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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