When I installed the plug in harness for my trailer when I step on the brakes the trailer lights go out. All lights including signals and tail still work ok on the truck , Any help appreciated
Trailer wiring harness
Oct 25, 2003
12 Replies
make, year ......
Check all of your wires, sounds like a bad ground.
Sounds like a grounding issue. Be advised, the hitch is not a good enough ground.
I also would make sure you have a good ground. Don't rely on the ball/trailer hitch to provide it with just the metal to metal contact when coupled together. Have an actual ground wire as one of the trailer plug connections.
Do the lights go out even when sitting still or is it something that happens only when you are moving?
It is just the running lights that go out? How about the brake and signal lights? Do you have electric brakes on the trailer? If so do they work?
Dick snipped-for-privacy@att.net
At this point I will have to guess you are not using the proper wires from the truck harness.
The following site includes a table of the GM wire code.
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