SB-10056364-4046
File in Section:

Service Bulletin

Bulletin No.:
Date:

PIT5311
August, 2014

PRELIMINARY INFORMATION
Subject:

Check Trailer Wiring Message and/or Service Trailer Brake With DTC C1114

Models:

2014 Chevrolet Silverado 1500
2015 Chevrolet Silverado, Suburban, Tahoe
2014 GMC Sierra 1500
2015 GMC Sierra, Yukon Models

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern
Some customers may experience an intermittent "Check Trailer Wiring" message and/or a "Service Trailer Brake"
message with DTC C1114 on vehicles equipped with ITBC (Integrated Trailer Brake Controller) RPO JL1. Below are
two possible causes for these concerns..
Note: The below two possible causes can also effect a truck equipped with an aftermarket trailer brake controller.
1. These concerns may be displayed each time the trailer's running lamps, turn signal lamps, or brake lamps are
turned on, especially if the trailer is equipped with a large number of lamps. This condition is most likely caused
by insufficient trailer grounding and the trailer ground wiring will need to be repaired and/or upgraded.
2. These concerns could be caused by a poor connection at the 7-way trailer connector. 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. Also, they may 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. 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.

Recommendation/Instructions
1. Inspect and clean the ground wire (normally white wire) connection on the trailer side of the 7-pin connector.
• Make sure that the wires inside the trailer side connector are clean and securely fastened
• If an electrical junction box exists on the trailer, make sure the wires inside the junction box are clean and
securely fastened.
• Once this procedure is complete, check to see if the condition has been corrected. If the condition still exists,
perform the following procedure:
1.1 Remove the original trailer ground wire (normally white wire) from the trailer side of the 7-pin trailer
connector.
1.2 Install a ring terminal (PN 12103512 or equivalent) to this wire and fasten the ring terminal to the metal or
aluminum chassis of the trailer using an M6x1x20 self taping phosphate zinc coated screw (PN 11515925 or
equivalent).
• Pre-drill trailer chassis location with a 3/16" hole.
• Make sure the trailer chassis location is clean of paint or coating material prior to installation.
• Galvanic corrosion between dissimilar trailer and screw metals may require that this ground location be
periodically cleaned.
1.3 Obtain a sufficient length of minimum 10 gauge (5.0 mm) white wire and fasten with ring terminal (PN
12103512 or equivalent) to the trailer chassis at the same location as the original ground wire.
1.4 Install and fasten the other end of the new ground wire into the trailer side of the 7-pin trailer connector

1.5 Install conduit on the original and new trailer ground wires and secure the conduit to the existing trailer
harness.
2. 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; by using a Pollak Heavy Duty 7-Way (Trailer Side)
Connector Plug will ensure proper fit when the two connectors are mated. Pollak's website is:
www.pollakaftermarket.com/. Once at the home page select "Connectors" and then "Heavy Duty 7-Way Plugs
and Accessories".
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 (with a GM CCA Customer Care and After sales Part) along with the trailer's 7-way
connector plug to a Pollak HD.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is
resolved without completing every step, the remaining steps do not need to be performed.