They were geting ready to put this truck away for the winter after they washed it the heater fan and lights wouldnt work. I looked at it and there is a black box on top of the fuse/breaker box that has a cable from the bat on one lug and another lug with several wire that is thier power supply but it was only hot on one side it also has 3 small wires one is hot one is ground and the other one i touched a hot wire to it and something clicked and every thing started working???
Post a picture of what you are talking about if you can, not quite following on the 3 small wires. Is it still working now?
That's internationals cab relay. They work great until the contacts get worn, then it's time to replace. Easy to get to.
Does this relay stay on all the time? I unpluged the 3 wires conection and it stayed on. This summer the AC compresser wouldnt stay ingauged would this have any thing to do with that.