Ok, I know the big orange wire is the charge wire, going to the rear of the van. I'm not getting voltage there. I have all relay sockets populated, as well as all fuse sockets. The trailer brake circuit works fine, as do all the trailer lights. I have the auxiliary battery. Is there another wire I have to connect? I see a connector with large wires in it right down the inboard side of the main battery. It has orange, yellow, and blue...I think it's some sort of upfitter connector though, but I'm not sure.

This is all on a 1993 E350 Super Club Wagon

I don't have the owners manual. Which sockets are the ones for the trailer relay and fuses?

Thanks!

 

if you're still looking for the answer, PM me. I might have a solution.