Running Lights Work Intermittently On Trailer Towed by 2009 Toyota Highlander with Curt Harness

Question:

I installed on my 2009 Highlander Hybrid. After working for about one year I now have intermittent problems getting a live supply on brown wire. Testing at back of car connection shows no juice in brown wire only. Other wires are live. What should I check?

asked by: Mark

Helpful Expert Reply:

You can check the vehicle to see if the running light fuse or relay is intact and working properly. After that you can check the signal going into the converter box from the vehicle using a circuit tester like # PTW2979 if you do not already have one. If the signal is coming in fine from the vehicle with no issues but intermittent on the 4-Way end then the converter is bad and the harness will have to be replaced.

If the signal going into the converter is not correct than that means a wiring, fuse, or relay issue on the vehicle. Make sure that the 4-Way end on the vehicle and trailer is clean and free of any corrosion because that too can cause issues. The converter box ground could be moved to see if that helps.

And finally you can make sure the lights on the trailer are all grounded to clean and corrosion free metal surfaces. I have included some links that will help you to troubleshoot.

expert reply by: Michael H