Trailer Brake and Turn Signal Lights Do Not Work When Running Lights are Turned On

Question:

I have a Colman Pop up camper and a 2006 Honda Odyessey as the tow vehicle. Everything works OK except when I turn the running lights on the brake and both turn signals fail to work. If the running lights are off, the brake/turn signals work fine. THANKS FOR THE HELP

asked by: Aaron

Expert Reply:

It sounds like there is either a ground problem or the power draw is too much for the wiring system on the vehicle when the running lights are on. First, check the main grounds on the vehicle wiring harness and the trailer connector. All grounds should be attached to clean and corrosion free bare metal surfaces.

Check the trailer connectors on both sides for dirt and corrosion and clean them out. Next check the lights themselves. Many trailer lights ground through the mounting studs if there is no obvious ground wire. In either case make sure the lights are grounded to clean corrosion free bare metal surfaces.

Also check the trailer lights to determine how much power they draw. The wiring harnesses for the 2006 Honda Odyssey, like # 118438, are designed to only handle a max for stop/turn light of 2.1 amps per side and a max for tail lights of 4.2 amps total. If you go over this then it is too much draw on the converter and lights will not work and/or it can blow the converter.

expert reply by: Michael H