Another thing you could check if you have a tester is, na dthis happend to me. When I bought my last truck it didn't have a hitch on it for some reason so I had the dealership put one on, and do the wiring, when the bone heads did it they hooked the ground wire to the hot ground for the truck. On your vehicles you have 2 grounds, one is hot and one is not. Take our tester and put it in the hole that is for the ground wire to your vehicle and if the light comes on, that is your problem.
according to my 6yr old, mom it's real easy all you have to do is quakum, and killum