How to Test Trailer Wiring Harness with Parking Lights Always On on a 2006 Chevy Express Van

Question:

i installed this adapter in my 2006 chevy express van a few years ago. now when i plug a trailer in, my parking lights are on constantly, even when vehicle lights are off. the left and right brake/signal work good. is my unit faulty?

asked by: George

Expert Reply:

It sounds as if your converter is shorted out. To check, you can test the brown wire going into the converter, no trailer connected, with a circuit tester, # PTW2993 if needed. You should not have power with the taillights off. Then check the brown wire coming out of the converter, if you have power with the taillights off then the converter has been shorted somehow and will need to be replaced.

If the wiring harness functions normally with no trailer connected, then there is a problem on the trailer wiring somewhere, most likely a bad ground or a frayed wire that is contacting the trailer frame. Checking all of the trailer wiring and making sure all of the grounds are connected to paint, rust and corrosion free metal parts of the trailer frame should solve the issue.

If you replace the wiring harness, be sure to go over the trailer wiring and make sure there are no issues that could short the new wiring harness when you plug in the trailer. Test the connector without the trailer connected before plugging it into the trailer for the first time.

expert reply by: Robert G