I recently installed auxiliary lights, and auxiliary power for my spreader. I used relays for a 1991 f-150, and one of them has stopped working after 1 day of use-the one for the lights. Are these relays just not designed for extended use, or did I just get a bad one? I checked all power and ground, and everything is good, so I am positive it is the relay that went bad.

 

You're using starter relays for lights and auxiliary equipment? Besides way overkill, yes, they are meant for very short intermittent use. And way too expensive for this application. Your favorite auto parts store should have lighting relays like used for fog lights, etc. IIRC they are rated for about 30 amps and I'm sure are still under $10.

Be sure to use properly rated wire for your current load, i.e. don't try to pull 25 amps over 22 gauge wire.

Michael