Check Trailer Wiring and Trailer Disconnected Message on 2018 Chevy 4500

Question:

2018 4500 in dash brake controller, big tex trailer with electric brakes. started getting intermittent check trailer wiring, then trailer disconnected, not almost all the time. cleaned contacts at 7 pin, checked trailer wiring, and replaced one magnet due to frayed wiring still getting the message. if I back up slightly and go forward brakes will work for a minute then message comes back on. Electrical is not my area, used test light on 7 pin, nothing at blue wire with brakes depressed or controller manually applied. Not sure where my issue is.

asked by: Nathan B

Helpful Expert Reply:

It sounds like you're not getting a signal on the blue brake control wire at the vehicle 7 way connector. The blue brake control wire seems to be the most likely issue, but it could also be an issue with the ground wire as well.

Let's start by checking the blue wire on the 7 way on the vehicle and work your way back through that wire to make sure that it hasn't been cut or damaged; this could be shorting out by exposed wires touching the vehicle's frame. If that checks out, you'll also want to check the ground wire on the vehicle to make sure that is not damaged and that it is securely attached to a paint free and debris free spot on the vehicle.

If neither of these come back as the source of the problem, let me know and I can give you a few other things to look at in relation to the vehicle's in dash brake controller.

expert reply by: Erik B