Which Fuse on 2014 Ford F150 Protects Trailer Running Lamp Circuits

Updated 07/18/2020 | Published 07/17/2020

Question:

what fuse or relay controls the tail lights on trailer. All other trailer lights work. There is NO power on truck side for tail light connector

asked by: William J

Expert Reply:

There is one 20A fuse and one relay in the engine compartment fuse block for the trailer running lamps. The relay is in location # 6, and the 20A fuse is in location # 67.

Try swapping an adjacent relay into the # 6 location, to see if that makes a difference. Then, check the fuse in # 67. If it's blown, replace it but before you plug a trailer back in, you'll need to find out why the fuse blew.

Examine the trailer connector on the truck, looking for green or white corrosion on the pins, clean or replace the connector as needed. Then trace the running lamp circuit on the trailer which is typically a brown wire. Follow it all the way back to the trailer lamps, looking for pinched or broken wires, loose connections or cracked or worn wire insulation. Look for anything that would allow the copper conductor to short out on the trailer frame. Once the short is located and repaired, you should be good to go.

I'll link you to some trailer wiring troubleshooting articles that you might find helpful.

expert reply by: Mike L