What Would Cause Running Light Circuit On Multiple Vehicles To Stop Work When Hooked To New Trailer?

Question:

Have a 2015 Chevy express with 7 way trailer plug all Lts and brakes work on other trailers i have bought a new flat bed trailer plugged lts in to check before leaving dealer all worked just as was getting back on road noticed tail lights were out stopped and checked all lts were working on vehicle and trailer except running lts on trailer came on home connected to other truck and same thing happened I lost the power to the running lt prong on both vehicles that truck is a 1998 f 150.

asked by: Randy H

Expert Reply:

Based on what you're describing you need to check the wiring on the trailer, as it sounds like there's a short on the running light circuit causing the fuse to blow in the tow vehicle, which is why you keep losing that function on whichever tow vehicle you hook up.

You just need to cut out the damaged section of wiring out and replace it with some # 16-1-1 and heat shrink butt connectors # DW05744-5. Make sure the wiring is secured out of the way of any moving parts as well to prevent the issue from happening again.

expert reply by: Samuel C