22-NA-111

Service Bulletin
Bulletin No.:
22-NA-111
Date:
May, 2022
INFORMATION
Subject:
Information On Common Customer Trailer Side Faults
Brand:
Model:
Cadillac
Chevrolet
GMC
Model Year:
from
to
Escalade Models
2021
2022
Silverado 1500 –
(LTD, RPO J22, 12th
VIN Digit = 5 or
greater)
2022
2022
Suburban
Tahoes Models
2021
2022
Sierra 1500 – (LTD,
RPO J22, 12th VIN
Digit = 5 or greater)
2022
2022
Yukon Models
2021
2022
Involved Region or Country
VIN:
from
to
Engine:
Transmission:
United States, Canada, and Mexico
Additional Options (RPOs)
Condition
Some customers may comment that their trailer does not operate in the manner
expected.
• Trailer lighting is inoperative
• Trailer detection is not possible
• Trailer lights flash intermittently while the ignition/vehicle is OFF
• Trailer message displayed on the DIC
Cause
This condition may be caused by a poor connection on the customer’s trailer.
Customer Information
Trailer issues are NOT covered under warranty, but this procedure can be used to help
the customer understand any trailer related issues.
Discuss with the customer these scenarios and advise to correct the trailer wiring,
connector, update the trailer lights or add load resistors to the bulbs/lamps if they so
choose.
Service Procedure
Warning: This procedure is a guide to diagnose
trailer side problems. Read the service manual
before performing any work. Improper repair and/or
maintenance could result in death or serious injury.
Important: Service agents must comply with all
International, Federal, State, Provincial, and/or
Local laws applicable to the activities it performs
Copyright 2022 General Motors LLC. All Rights Reserved.
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.
Page 2
May, 2022
Bulletin No.: 22-NA-111
Fuses
Trailer Brakes
Tail Lamps
Backup
Lamps
Left Turn/
Stop Lamps
Right Turn/
Stop Lamps
Constant B+
Fuse
F63UA (40A)
X
-
-
-
-
-
Fuse
F74UA (30A)
-
X
-
-
-
-
Fuse
F82UA (30A)
-
-
X
X
X
-
Fuse
F84UA (30A)
-
-
-
-
-
X
Note: All trailering fuses can be found in the
under-hood fuse block.
Trailer Lighting System Description
When a trailer is connected to the vehicle, the Trailer
Lamp Control Module on the vehicle responds to the
operator’s lighting controls by applying voltage to the
appropriate control circuit to the trailer connector of the
vehicle. When the electrical connector from the trailer is
plugged into the trailer connector of the vehicle, the
voltage from the vehicle is then applied to the
appropriate circuit on the trailer and the corresponding
lamp on the trailer will illuminate. Fuse F74UA and
F82UA are the power supply fuses to the Trailer Lamp
Control Module. If a fuse is blown, an electrical fault
likely exists on the trailer causing the fuse to blow.
Trailer Connector
6081040
1.
2.
3.
4.
Ground
Tail Lamps
Left Turn/Brake
Right Turn/Brake
6081038
If equipped, the trailer wiring harness, with a 7-pin
connector and a 4-pin connector, is mounted on the
vehicle's rear bumper.
6081041
1. Left Turn/Brake
2. Tail Lamps
3. Reverse Lamps
Bulletin No.: 22-NA-111
4.
5.
6.
7.
May, 2022
Battery Feed
Right Turn/Brake
Electric Brakes
Ground
Common Trailer Faults
Trailers are known to have multiple areas of electrical
failure. Below is list of common problems that cause
electrical faults on trailers.
Note: It is normal for the DIC to display "Check Trailer
Wiring" when the trailer is disconnected from the truck
while the ignition is in the run position.
Loose Connections
The trailer connector is a common point of failure. A
loose/broken connection will result in intermittent
electrical issues or inoperative electrical systems on
the trailer.
Trailer lamp assemblies also have connections that can
become loose/bad over the life of the trailer which may
result in intermittent or inoperative lamps.
Wire nuts should never be used to service trailer wiring.
Wire nuts are not properly sealed for automotive use
and will allow moisture and debris into the electrical
connection which results in a loose/bad connection.
Faulty Ground Circuits
Ground circuits are usually connected to the frame of
the trailer using some form of ground connection made
by a screw/bolt. These connections may corrode and/or
become weak over time causing a loose/broken
connection. A faulty ground connection will not allow
the flow of electricity through the circuit resulting in
faulty lamp illumination.
Boat Trailers and/or Water Intrusion
Boat trailers are constantly submerged under water. If
the lamps and wiring of the trailer are not sealed
properly, water intrusion will usually result in an
electrical fault on the trailer and cause a high-current
condition which will usually result in a blown fuse.
Trailer Lighting Verification Procedure
1. Inspect the trailer side connector on the vehicle
and trailer for corrosion and/or visible damage.
• If corrosion and/or visible damage exists:
– Repair or replace the trailer side connector as
necessary.
• If no condition exists
2. Connect the electrical connector from the trailer
into the trailer connector of the vehicle.
3. Start the vehicle and select the “Start Light Test”
function through the trailering App.
Page 3
4. Verify the appropriate lights on the trailer turns ON
and OFF.
• If the trailer tail lamps do not turn ON
and OFF
– Verify Fuse F74UA in the under hood fuse
block is not blown.
• If the trailer turn/stop lamps do not turn ON
and OFF
– Verify Fuse F82UA in the under hood fuse
block is not blown.
• If the trailer backup lamps do not turn ON
and OFF
– Verify Fuse F82UA in the under hood fuse
block is not blown.
• If all the trailer lamps turn ON and OFF
5. A fault is not currently present with the trailer lamps
Vehicles with Trailering App
Vehicles with the Trailer Interface Module constantly
monitor for trailer connection status, trailer lighting
faults, and trailer theft deterrent purposes through the
lighting circuits of the trailer. Refer to your owner’s
manual for more details.
Trailer Connections Status
The flashing or flickering lights is a normal condition.
With a trailer connected and the ignition off, the Trailer
Lighting Control Module will periodically pulse the
lighting circuits of the trailer to verify it is still connected.
Depending on the configuration of the trailer lights, the
trailer lights may periodically flash as part of the trailer
connection detection or theft deterrent functions.
Connection Problem
If any of the trailer connections are lost, a message
about the connection issue will appear on the Driver
Information Center (DIC). Depending on the settings, a
Trailer Connected or No Trailer Connected status may
be displayed by the trailering app on the infotainment
screen.
Connection Trailer Lighting Faults Detected
The Trailering App System monitors for electrical faults
on the trailer lights. A message about the lighting issue
will appear on the DIC. The infotainment display will
also show the lighting issue in the Connection
Status view.
Diagnose View
This view will display the names of the trailer connector
pins, a graphic of the trailer connector, and a graphic of
the back of the trailer.
Any connector pin that failed will be amber color, and
the location of the corresponding connection will be
highlighted on the graphic of the back of the trailer.
The Running Lights connection may not detect partial
outages. Activate the light test to check all trailer lamps.
See “Light Test” following.
Page 4
May, 2022
Bulletin No.: 22-NA-111
Light Test
To help you check that all of your truck and trailer lights
are in working order, this feature activates your brake
lights and turn signals so you can perform a visual
inspection.
Warranty Information
No warranty labor operation is provided for concerns
related to the trailer.
Version
1
Modified
Released May 24, 2022
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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