At your battery junction box there is arelay for lamps, but I think if you are saying they go out whn you hook up trailer then you have a bad ground probably either ogoing to the trailer or on the frame of the truck
April, 2, 2012 AT 1:41 AM
All other truck lights work can't find fuse for dumpbody
April, 2, 2012 AT 2:11 PM
It's not a fuse check the ground from the truck to the trailer, if they work without the trailer hookup then it's a trailer problem or the connector.