No Power On Wiring Harness When Brakes Are Applied

Question:

2003 chevy silverado. I have checked and I do not get any power on the wiring harness when applying the brakes. All brake lights are working but the trailor brakes are not. This was working but has stopped. ..help

asked by: Rick P

Expert Reply:

If you have a trailer connector that is not working properly you need to use a circuit tester # PTW2993 to determine the source of the problem at your truck first. This will allow you to see if a signal is on the appropriate wires. If you are getting signal on the posts on the truck you know the problem is in the trailer wiring, and if you are not getting signal there, you have isolated the issue to the truck first. I have a very detailed help article attached called Troubleshoot Your Trailer Wiring, it has instructions and videos to help solve this issue.

Also look for pinched or cut wires; these are often found when wires are routed above suspension components or behind taillights. Attached is a very detailed troubleshooting video on how to test the 4-pole and modulate.

Testing the brake controller is fairly easy. if you have a proportional brake controller, sever the brake output wire and then apply the manual slide. Using the circuit tester # PTW2993, you should get output to the trailer brakes. Use the manual override and if it works then you know the brake controller is not the issue. If it doesn't work, then the problem is farther back either in the vehicle wiring or on the trailer. I have troubleshooting brake controller videos attached.

If you don't get signal coming from the controller, it needs to be replaced. If you are getting signal from the brake controller, then the problem is somewhere between there and the 7-way and you will need to trace the wire.

Sometimes there can be a fuse that needs to be replaced as well.

If you still can't find the problem, let me know so you can keep troubleshooting with what he has found.