I have a 05 F150 super crew lariate 4x4. The trailer I have has a short in the running light circuit somewhere and blew a fuse in the truck. The fuse is for the running lights, fog lights, and gauge lights. I replaced two fuses today and fixed all those issues but now when I turn the switch for the lights off the running lights don't go off. Any ideas of what it could be would be a great help.

 

Might be the relay switch is stuck closed. Might be fried. If the fuse was slow to blow, the power surge can do that.

I don't know where that particular relay is located, but it's usually in a waterproof box under the hood, near the firewall. Relay location diagram is under the lid, just like the fuse box. You can take it out and bang it on something hard then put it back in to see if it was stuck. If that doesn't work, take it to the auto parts store and get a new one. I've had them as cheap as $5 and as much as $25.

Wait, though, is it only when the trailer is hooked up, or when unhooked? I assumed unhooked.

 

Ya this is when it is unhooked. I am working on rewiring the trailer. I was also just told if there is any corrosion in the seven trailer plug it could cause this. Any thoughts on that?