NHTSA ID Number: 11013242
Manufacturer Communication Number: 21-NA-155
TSB/Document Date: 2025-01-30
Summary
This informational bulletin advises the technician to check for faults that may be caused by the trailer otherwise found by a possible faulty trailer connector.
Bulletin No.: 21-NA-155
Service Bulletin
Date: January, 2025
INFORMATION
Subject:
Brand:
Information on Check Trailer Wiring Message and/or Service Trailer Brake
Displayed on Driver Information Center (DIC) - DTC C1114 Set
Model:
from
to
Escalade Models
2021
2025
Silverado 1500 (New
Model)
2019
2019
Silverado 1500
2020
2021
2022
2022
Silverado 1500 - LTD
(RPO J21, VIN Digit 5
= W / Y)
Chevrolet
Silverado 1500 - New
(RPO J22, VIN Digit 5
= A / D)
Silverado 1500
2023
Silverado 2500HD/
3500HD
2020
Suburban
Tahoe
from
to
2021
2019
2019
Sierra 1500
2020
2021
2022
2022
Sierra 1500 - New
(RPO J22, VIN Digit 5
= H / U)
VIN:
2025
Sierra 1500 (New
Model)
Sierra 1500 - Limited
(RPO J21, VIN Digit 5
= 8 / 9)
GMC
Model Year:
Sierra 1500
2023
Sierra 2500HD/
3500HD
2020
Yukon Models
2021
2025
Involved Region or Country
North America, Middle East, Chile (West), GM Korea Company, Thailand (ASEAN),
Paraguay
Additional Options (RPOs)
JL1 (CONTROL-INTEGRATED TRAILER BRAKE)
Copyright 2025 General Motors. All Rights Reserved.
Page 2
Condition
January, 2025
Bulletin No.: 21-NA-155
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.
Cause
Note: The below two possible causes can also affect a truck equipped with an aftermarket trailer brake controller
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 7way (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.
• 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.
Information
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, use the EL 52641 Trailer Presence
Simulator Tool and refer to Document ID: 5627183: PIT5509L: Diagnostic Tip - Check and/or Service Trailer
Brake System message DTC C1114 in SI.
Bulletin No.: 21-NA-155
January, 2025
Page 3
The Following failures are the result of trailer side connection issues:
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 – NonWarranty Issue.
Page 4
January, 2025
Bulletin No.: 21-NA-155
5867995
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.
Bulletin No.: 21-NA-155
January, 2025
Page 5
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
Page 6
January, 2025
Bulletin No.: 21-NA-155
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
6
Modified
Released September 21, 2021
Revised June 14, 2022 - Added 2022 to Model Year and Updated Information section.
Revised January 11, 2024 - Added the 2023 - 2024 Model Years.
Revised April 08, 2024 - Added Korea to Involved Region or Country section.
Revised January 09, 2025 - Added EL 52641 Trailer Presence Simulator Tool to The
Following Failures are the Result of Trailer Side Connection Issues - Non-Warranty Issue
section.
Revised January 16, 2025 - Added 2025 Model Year.
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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TSB/Document ID: 21-NA-155
Replacement Service Bulletin Number:
MFR Communication Date: 2025-01-17
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: ELECTRICAL SYSTEM
MFR Component System:
MFR Component Subsystem:
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