I converted to headlight relays a year ago or so, but lately every time I go to use the headlights the fuse is blown. I replace it and it works just fine the whole time, but the next time I need them the fuse is dead again.
Any thoughts on this one?

 

I would pull the relays and give them a test. It sounds as if one is hanging and not fully releasing the circuit. If it is not there, try your camper or trailer wiring harness. Mud in the connectors can get wet and create a continuity power feed from the RV hot feed back into the tailights, and through your light switch. The light switch itself can drop a contact and do this too.

 

It sounds like you may have a short somewhere. My brother was having a similar problem and found out that it was the wiring for the trailer that was shorting.

 

It's just blowing the headlight fuse (30 amp) that I put in with the relay setup. It's not blowing the rest of the lights, so I know it's something to do with my added components. I'll trace everything and let you all know what I find... Thanks!

 

Mark, is it possible that something grounded is touching the 87a terminal on one of the relays? That terminal is hot when the relay coil is turned off.

 

That seems like a good place to start, thanks Dave.