| Subject: | "Check Trailer Wiring" Message Displayed On DIC |
| Models: | 2007-2009 Chevrolet Silverado |
This PI was superseded to update model years. Please discard PIT4366A.
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 in vehicles equipped with ITBC (Integrated Trailer Brake Controller) RPO JL1 and no DTC's stored. This message 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.
Recommendation/Instructions:
To correct this condition, perform the following procedure:
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:
- Remove the original trailer ground wire (normally 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 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. |
- Obtain a sufficient length of minimum 10 gauge (5.0 mm) 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.
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.
