Rear Window issues

[LEB Ben]

Alright fellas, got another Bronco problem...the rear window. The window worked perfectly Friday from the key and the dash. I went to roll it up yesterday and nothing from either. I haven't really dug in to it much, but all fuses are good, and I'm getting power to the gate. I also hear the switch engaging and disengaging. I pulled the access panel and didn't see any anything unplugged or blatantly wrong. Any thoughts or ideas? Is the motor shot?

 

[m78]

If the motor runs , you might get by with the gear drive rebuild kit. If anybody offers it.

 

[Ranger429]

Take the two clip connectors for the wiring harness going from the main feed line to the motor and cut them off. Mine did the exact same thing, no power to the motor and good power at the connector. I replaced the connector with blue butt connectors and the window works like a charm.

I have the same style connector on the crews harness for the rear taillights at the firewall and it is the same problem, not allowing power thru it. I ran a temporary jumper wire and the lights work fine. Those connectors go to crap after a while.

 

[73F100Shortbed]

I don't know if it works like the newer ones, but make sure the door is closed all the way. On an 88 I had the same problem. After closing the door twice it worked. Even though the door seemed closed it wasn't causing nothing to work. I'm not sure if 79 is the same, but worth a look.

 

[LEB Ben]

Thanks Scott...luckily it's been nice this week, so I haven't had to worry about the rear getting wet. I'll give it a go this weekend.


Sean...you just suck...haha. Thanks for the suggestion, I don't think 79 has any safety switches...because I've been able to roll my glass up with the tailgate in any position. But I did notice a latch had shifted...and taking some force to get it closed...so I'll give it a look as well.

 

[Ranger429]

A 78-79 also has a safety switch Ben. Originally the latches need to be clicked closed in the 2 positions as Sean stated. In the center of the tailgate at the bottom is a switch that is activated by a rod connected to the handle assembly. It sounds like yours has been rewired to work all the time if the latches are still in the open position.

 

[LEB Ben]

Thanks for clearing that up for me Scott.



Alright...here's the deal, I got toying around with this thing over the weekend with a test light. I have power to the switch and power all the way to the last plug. There are two wires, a red with yellow stripe and a yellow with red stripe. When I turn the key in the gate one way, one lights up and when I turn the key the other way, the other wire has power. And this is how it works all the way down to the last plug before the motor. I noticed the last plug looked like it had some heat damage and burning. I also noticed that it looked like this stretch of wire from the plug to the motor had been replaced with plain red wire and plain yellow wire. So anyway, I stick my test light in one wire and turn the key, acts fine. I put the test light in the other wire and turn the key, it starts smoking and no light, however, I turn the key back the other direction and it lights up with no smoke.


So my thought is the plug is trashed and causing a short and arc over. Does this sound reasonable?

 

[greystreak92]

Ok, the switching operation here is much simpler than it may seem. The wiring (other than the smoking and heat) sounds like for at least part of the system is fine. The switch (and in the case of the tailgate glass, switchES) is/are fed both positive and negative. Pressing the switch one direction sends positive to one wire and negative to the other. Push it the other direction, and the positive and negative switch wires but its the same wires. This creates the directional change at the motor.

With the "smoke" in one direction, the wire that SHOULD have positive in that direction has shorted to the body/frame of the truck somewhere. This is what is causing the smoke and overheating of the wire. So, in this case to be certain, you can either trace both wires to the motor or use a voltage meter instead of just a test light (since a test light lights up no mater which way the electricity flows through it). The meter will tell you which wire is getting positive voltage. Of course, if you don't have access to a meter, you can always carefully follow the wiring from the motor all the way back to the last known point in the harness that there is no problem.

 

[73F100Shortbed]

Do what greystreak says and look for short. Also you will want to change the connector if it looks burnt. If you can't find a good connector you can just use butt connectors to join the wires.

 

[LEB Ben]

^^^Well see, that is where the issues lies, I'm getting no movement out of the motor, and from the last plug to the motor (so the last 12" of wire) is what's fubar'd IMO. Because prior to that plug, everything seems to be in working order.


So for the time being, cut off the heat affected plug, put some spade connectors on the wires and see if I can get the motor to work????

 

[73F100Shortbed]

So for the time being, cut off the heat affected plug, put some spade connectors on the wires and see if I can get the motor to work????

Yep

FWIW, if you want to spend the money, which is well worth it for testing electrical stuff imo, get a power probe III

http://powerprobe.com/powerprobe/PP3.html

 

[LEB Ben]

To be quite honest, I was a little worried clicking that link, expecting something Austin keeps under his pillow. But that thing does look pretty awesome. Google says it's right around $90 plus tax.

 

[73F100Shortbed]

To be quite honest, I was a little worried clicking that link, expecting something Austin keeps under his pillow.

hahahaha

 

[Ranger429]

You can disconnect the motor itself and bench test, don't know if you tried that yet.

 

[polarbear]

That would be the power tailgate window that, when I mentioned was the source of persistent issues, was flat told by everyone here that had one that they never fail...

 

[LEB Ben]

Not that they never fail, because all parts fail...just that it's not that big of an issue. There's 31 years of use out of this motor...I consider that pretty good, and not a problem area. BTW...it's not the motor that failed anyway, it was a bare wire that shorted and melted the plug.


JBG has that harness for $250...I think I'll just cut back the bad wire...might even replace and use some spade connectors.