Rear window troubleshooting help

[Hiney]

I just bought my first Bronco a few months ago and I'm getting around to fixing some minor things now that most of the major things are fixed. It's a 91 EB that I bought with a 3 inch body lift, 1 inch add-a-leaf, M&T Classic II's with 35x12.5's, fender flares and a leaky timing cover, rear main, oil pan and valve covers. I've since fixed the leaks (yanked the motor and did all new gaskets/seals replacing everything but rings and bearings in the bottom end), installed a new cam (Edelbrock Performer-Plus) with a timing set, headers (POS pacesetter's that I wish I never bought) and full exhaust (Bassani 3 inch off-road y-pipe with a 3 inch in, dual 2.5 out flowmaster 40).

So one of the idiot P.O.'s decided it would be a good idea to cut the harness going to the tailgate... I've since fixed that, however I've been troubleshooting the window not working. The window operated just fine if I put jumper wires into the motors connector and put it on a battery (this is how I've been rolling the window down for the last few months) proving the motor is fine, but the key switch never worked, nor did the dash switch.

I spent a little time with it last sunday, hooked up the ground that wasn't attached previously, and got what seems to be the latch safety switch working properly. The problem I was having was I had juice (+12V when the key switch on the gate was turned one way and -12V when turned the other way) however the motor would NOT move... Very odd, I figured it was an amperage issue but the dash switch didn't work either. So I ordered a new switch, installed it tonight and nothing changed EXCEPT the key switch works now. So I plug the old dash switch back in and the key switch STILL works! I blame this on the fact it's raining out tonight so I have a bad ground somewhere in the circuit I think.

My question is why isn't my dash switch working? There are 6 wires going to it and only 3 go back to the tailgate. I'm to assume one is power, another is ground, but I'm not sure what that last is. Is there a common thing that goes bad under the dash/a bad ground somewhere causing this to happen?

Jeremy

 

[Seabronc]

You are almost there. If you have 12V at the switch and the safety switch is Ok, then the problem is in the ground return path. To make both the dash and tail gate switches work, they swap the function of the wires at the switch. The black with white stripe should be hot at all timews and is the tail gate power source. When you turn the key, one wire supplys the power to the motor lead and the other returns to ground through the dash switch. When you turn the key the other way it reverses the wire functions. Attached is a diagram for a 92, but they are all the same, Ford doesn't re-invent the wheel for every year vehicle.

In that return path, is a connector that is just under the left rear bumper by the tub support member, a common location for failure due to corrosion. My vehicle also had one behind the tail light but I believe that a 91 does not. Also it could be the dash switch as it has contacts that must vbe made that are used for the ground return. The ground point is under the dash.

Good luck,

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