I bought it on craigslist, still sealed in its box.

Its an older unit... But a nice one. It has 3 wires, ground, switch and Positive.

I tested it on my tractor battery and it worked. So, I hook it all up... and nothing. I take it out, test it again, and still nothing.

Its like it just died. And the inline fuses are in tact. Thoughts?

 

Some units had a small glass fuse inside the case on the PC board.

 

is there a fuse on the positve wire?

 

Bad ground?

 

crossed wires and it got toasted?