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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1155 (TRAILER BRAKE CONTROL SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESSYMPTOMS - TRAILER BRAKE CONTROLSSYMPTOMS TESTING
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6

Symptoms Testing

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Symptoms Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Some customers may experience an intermittent Check Trailer Wiring message in vehicles equipped with ITBC (Integrated Trailer Brake Controller) with no DTC stored. This message may be displayed each time the trailer's running lamps, turn signal lamps or brake lamps turn on - especially if the trailer is equipped with a large number of lamp loads.

Check Trailer Wiring Message on the DIC

  1. This condition is caused by insufficient grounding between the trailer and vehicle.
    • To correct this condition, perform the following procedure:
      • Inspect and clean the ground wire (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:
      • Remove the original trailer ground wire (white wire) from the trailer side of the 7-pin trailer connector.
      • 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 a 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.
    • Obtain a sufficient length of minimum 10 gauge (5.0 mm2) white wire and fasten with ring (PN 12103512 or equivalent) terminal to the trailer chassis at the same location as the original ground wire.
    • Install and fasten the other end of the new ground wire into the trailer side of the 7-pin trailer connector.
    • Install conduit on the original and new trailer ground wires, and secure the conduit to the existing trailer harness.
  2. Verify the condition has been corrected.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.