Troubleshooting a Trailer Dome Light On a 2015 Ford Super Duty

Question:

I just bought a 24 foot enclosed car hauler all lights work on the trailer brakes work but the interior dome lights don’t work checked all fuses and relays in the truck and they’re all there any ideas to get my dome lights to work it don’t seem like I’m getting 12v power at the back of the truck I took the trailer back to the dealer they plugged it into their box and the lights worked fine so I know it’s somewhere on my truck is the problem

asked by: Tob

Helpful Expert Reply:

You'll want to start by using a circuit tester like part # 4PTW2993 to check that there is power actually reaching your 7-way plug. Start with the plugs themselves, clean their contacts and rewrap them with new electrical tape and dielectric grease. Sometimes reconnecting this point can fix the entire system.

Then, work backwards, following the wires and checking them for kinks, damage, dirt or broken or loose connections. Repair and replace the wiring and ports as you need to. You may also check your engine compartment for any fuses or circuit breakers that are wired to the battery and ensure they're in working order.

If this doesn't fix the problem, you can use a length of part # 10-1-1 to wire directly back to the trailer and bypass the dome light or replace the 12-volt's direct line. I've included a link back to another question that details how to directly wire the trailer through a battery connection if you have no need or ability to use the 7-way.

expert reply by: Jacob W