I recently acquired a 79 Wagoneer and the seller told me the rear window didn’t work but that there were 2 unattached black wires inside the access panel that he didn’t know where they went. I’ve looked at the wiring diagram for this vehicle however it’s doesn’t show all the wires in the harness that come through the tailgate’s plastic tube (at least that I was seeing through the rear access panel). I know the smaller gauge black and white wires are for the license plate light,the other wires are accounted for on the diagram and the orange wire powers the rear window defogger. What does the larger gauge black wire from within the harness attach to? There is also another unattached black wire that is attached and grounded on the same threaded stud as the license plate ground, what does the un-attached end go to?
When I took everything apart and removed the rear window and regulator I also noticed the ground wire for the rear defogger was broke off at the solder joint on the glass (there wasn’t a ground wire attached for the defogger). I originally thought my two unknown back wires were supposed to be connected together, that was until I realized the solder joint had failed on the defogger ground. Now I’m thinking the black wire from the plastic tailgate’s tube wire harness is supposed to be the ground for the defogger. If that’s the case what is the other back wire’s purpose, this is the wire where one end was grounded and attached along with the license plate ground wire?
Possibly it was a previous owner who installed and attached a ground wire for something else? Either way I have an un-accounted for black wire, what’s it for?
Before I did anything and or opened the access panel I had assumed the unattached black wires the seller mentioned were the ground wires for the window motor. However, that was before I saw the wiring diagram and realized how both tailgate window switches were wired and that the electric window motor is actually grounded through the front dash switch. I should also mention the rear tailgate toggle switch was broke so I assume that’s why the window didn’t work. Any clarification before I install the new switch would be appreciated. It shouldn’t be an issue but before I install the newly purchased $75.00 switch I thought I’d reach out for clarification and help.