NHTSA ID Number: 10235399
Manufacturer Communication Number: 20-NA-198
TSB/Document Date: 2023-05-03
Summary
This technical bulletin provides repair information to correct a customer concern of seeing the trailer running lights shut off due to excessive load on the running lamp circuit.
Service Bulletin
Bulletin No.:
20-NA-198
Date:
April, 2023
TECHNICAL
Subject:
Brand:
Trailer Running Lights Shut Off Due to Excessive Load on the Running Lamp Circuit
Model:
to
Silverado 1500
(New Model)
2019
2019
Silverado 1500
2020
2021
Silverado 1500 LTD
(RPO J21, VIN Digit
5 = W / Y)
2022
2022
2020
2023
Sierra 1500
(New Model)
2019
2019
Sierra 1500
2020
2021
Sierra 1500 Limited
(RPO J21, VIN Digit
5 = 8 / 9)
2022
2022
2020
2023
Silverado
2500HD/3500HD
Model Year:
from
Sierra
2500HD/3500HD
Date Breakpoint:
from
All
All
to
Involved Region or Country
North America, Middle East, Argentina (Mercosur), Brazil (Mercosur), Bolivia (West),
Chile (West), Colombia (West), Ecuador (West), Paraguay (West), Peru (West), Uruguay
(West), GM Korea Company, Singapore, Phiippines, Egypt, Other Africa, South Africa.
Additional Options (RPOs)
Equipped with INDICATOR-TRAILER INFORMATION (U1D)
Condition
Some customers may comment that the running lamps may illuminate for a second or
two, and then go out when operating a trailer running lamp circuit with more than 7-8
amps of current draw. On vehicles with LED lighting, the owner may have concerns with a
flash of the lighting about once every 10 seconds.
Cause
The cause of the condition may be that trailers with incandescent running lamps may
have in-rush current that exceeds the trailer lighting module limits for current flow. And
that monitoring voltage may illuminate LED lights even when trailer theft deterrent is not
enabled.
Additional Information
On 2019 Model Year vehicles, equipped with U1D, use the K68 Trailer Lighting Control
Module to control all trailer lighting through pulse width modulated (PWM) voltage. The
Trailer Lamp Control Module has a current handling capability on the running lamp circuit
of about 9 amps. On a trailer with a large number of incandescent lights, in-rush current
can exceed 20 amps before it settles back to around 8-9 amps. During this inrush or
"marriage" current period, the Trailer Lamp Control Module may see the inrush current as
an "overload" and go into protection mode.
On 2020 — 2023 Model Year vehicles, there may be complaints about either trailers that
cannot be properly detected, or complaints about light flash related to trailer connection
monitoring on trailers with LED lighting.
Install a 2021 design module and re-pin the running lamps to pin 25 for the running
lamps. (2019 model year only). This requires a terminated lead to be inserted into cavity
25 on the chassis harness X1 connector. Wiring connected to pin 5 on the X1 will be cut
and reconnected to Pin 25. Terminal in cavity 5 will remain, be blunt cut, and sealed with
a closed end duraseal splice to prevent water entering through pin 5.
This also changes the trailer connection detection flashing of LED lighting from every 10
seconds to every 42 minutes. (Connection detection will still be enabled if trailer theft
deterrent is enabled).
Copyright 2023 General Motors
LLC. All Rights Reserved.
Page 2
April, 2023
Bulletin No.: 20-NA-198
Correction
5652571
For 2019 models ONLY, Follow the steps in the Service Procedure below, and move
circuit 2109 on the Trailer Lamp Control Module from X1 cavity 5 to X1 cavity 25, and
install new Trailer Lighting Module.
For 2020 — 2023 models ONLY, No wiring changes are required. Confirm the Condition,
Plug in a new Trailer Lamp Control Module, confirm the issue is fixed.
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.
Important: If both trailer tail lamp codes are present on
a 2019 Model vehicle, please review to make sure the
re-pinning service procedure has been fully performed.
If the replacement Trailer Lighting Module is installed
on a 2019 vehicle without doing the wiring service
procedure, DTC B3885-04 Trailer Left Tail Lamp Circuit
and DTC B3886-04 Right Trailer Tail Lamp Circuit will
set when a trailer is connected.
• For 2019 models ONLY, the complete
Service Procedure must be completed.
• For 2020 — 2023 models ONLY, jump ahead
to step #14 and install the new Trailer Lamp
Control Module.
1. Raise and support the vehicle. Refer to Lifting and
Jacking the Vehicle in SI.
2. Lower and reposition the spare tire, if necessary.
Bulletin No.: 20-NA-198
April, 2023
Page 3
5209978
3. Locate the Trailer Lamp Control Module (2) and
disconnect the chassis harness X1 electrical
connector.
5652574
5652572
4. Cut off the tie strap retaining the wiring harness
and remove the cover from the connector.
5. Pull the wiring harness out of protective sleeve,
and trim back previous tape to access the wiring.
Page 4
April, 2023
5652575
Bulletin No.: 20-NA-198
5652578
7. Release the 4 tabs on the Terminal Position
Assurance (TPA) and pull slightly upward to
partially release it from the connector housing.
5652576
6. Locate the Gray/Brown wire, at pointer (1),
connected to cavity 5, and cut the wire
approximately 7.62 cm (3.0 in) from the connector
body. The wire will be re-located to cavity 25 (2).
5662018
Bulletin No.: 20-NA-198
April, 2023
5652580
8. Remove the seal from connector cavity 25 and
install the new terminated lead (1) into this cavity.
Ensure the terminal locks into place by pulling back
gently on the wire.
Page 5
5662021
10. Crimp a salmon Duraseal splice sleeve onto the
striped end of the wire stub in cavity 5 of the
connector. Attach the harness side of the grey
brown wire to the end of the terminated lead that
was just installed into cavity 25, using another
salmon duraseal splice sleeve.
5652578
9. Gently press down on the TPA until all 4 tabs
re-engage with the connector and are fully seated.
5662022
11. Use the Ultra torch to shrink the spice sleeve
around the wire and also seal the open end. Use
the Ultra torch to shrink the splice sleeve around
the grey/brown and white terminated lead wires.
Refer to the Weatherpack™ Wiring Repair section
of Wire to Wire Repair. in SI.
Page 6
April, 2023
Bulletin No.: 20-NA-198
12. Using Woven Polyester (PET) Electrical/
Anti-Abrasive Tape, or equivalent, re-tape the
harness where the previous tape was removed and
reposition the harness back inside the sleeve.
13. Reinstall the connector cover. Replace the tie strap
that was removed previously.
14. Install the new trailer lamp control module. Refer to
Trailer Lamp Control Module Replacement, in SI.
15. Reconnect the connector.
16. Remove the support and lower the vehicle.
Parts Information
Causal
Part
N/A
5652583
Description
Part
Number
Qty
WIRE,SPLICE
(TERMINATED
LEAD)
13575368
1
MODULE ASMTRLR LP CONT
13554026
1
SPLICE,WIRE
(SALMON)
19300089
2
Warranty Information
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
5480858*
New Trailer Lamp Control Module Replacement
0.3 hr
Add
Move Circuit 2109 on the Trailer Lamp Control Module (2019
Models Only)
0.7 hr
*This is a unique Labor Operation for Bulletin use only.
Version
7
Modified
Released September 28, 2020
Revised October 23, 2020 – Revised Text in Several Procedure Steps to Better Clarify
Repair, Added Graphic, Updated Parts Information
Revised December 04, 2020 – Added 2020 Model Year and Updated Labor Operation
with Add.
Revised January 29, 2021 – Revised Service Procedure to Note it is Necessary to
Contact TCSC For Repair of 2019 Model Year Vehicles Only. It is Not necessary to
Contact TCSC for 2020 Model Year Repairs.
Revised April 07, 2021 – Updated Service Procedure for Trailer Lamp Control Module
Replacement, Updated Parts and Warranty Information.
Revised August 09, 2020 – Added a First Important to Service Procedure and Added a
Lead Sentence to the Second Important.
Revised April 05, 2023 — Revised Part Information with Updated Module Part Number.
Added HD Models and Years.
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: 20-NA-198
Replacement Service Bulletin Number:
MFR Communication Date: 2023-04-05
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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