Troubleshooting 5th Wheel Wiring Harness and Trailer Brake System Error on 2017 Chevy Silverado 1500

Question:

I just installed the Demco 5th wheel wiring harness #DM8555001 on my 2017 Chevy Silverado 1500. Now every time I start my truck I get a ‘Trailer Break System’ alert on my display panel. Once I press to dismiss it, it stay gone until the next time I start my truck. This never occurred until I installed the Demco wiring harness. Do you have any suggestions?

asked by: Paul K

Helpful Expert Reply:

It sounds like a connection issue. I recommend removing the connections, checking for even the slightest bend in pins, and adding dielectric grease # 11755 to keep moisture and debris out. I recommend doing this at all 3 connection points of your # DM8555001 harness and then also adding that grease to the 7-way under the cover on both units.

This is the first I've heard of this issue with a 2017 model and also the first I've heard of the issue tied to installing a 5th wheel or gooseneck harness but if the connection troubleshooting doesn't solve your issue, there is a relay near your rear axle that has been an issue for years with throwing that alert even when things work correctly. Some models had the relay on the frame rail and others above the spare tire.

expert reply by: Jason S