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Tailgate window issues

MrTruck805

MrTruck805

1/2 ton status
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Hi all,

Recently I've been having some issues raising the rear tailgate glass on my 89 K5. I also could not lower the tailgate (I understand the safety mechanism could be an issue here?). So I took off the access panel, disconnected and reconnected everything I could and it worked. However after lowering the glass I again cannot put it back up. This time I can lower and raise the tailgate though. I can see and hear the blue cable actuating when I turn the key to raise the glass but nothing happens. Any ideas? Got some rain coming soon. Here's a pic below to see what I'm working with.

2w50pb5.jpg
 
For the time being, disconnect the blue cable from the transmission and connect the square cable that you see to a drill to raise it back up. Will explain what to check later when I have more time.
 
Thanks for the tip about the drill. Worked like a charm! I guess the issue is something upstream of that blue cable.
 
After rereading the problem it sounds like something else is going on than I originally thought. Looks like someone has been in there messing around already. Sounds like the motor works but does it bog down when it’s all connected? Does the window raise really slowly? The noise that you heard could be coming from stripped gears inside the transmission. Also look at either end of the shaft of the blue cable to make sure they’re not rounded off, likewise to where the cable attaches on either end too.
Also, the safety mechanisms (the safety switch next to the latch inside the gate on the driver’s side) won’t allow the motor to work without the gate being closed, so that’s not the issue. There’s also a safety mechanism (mechanical) that won’t allow the handle to operate unless the window is all the way lowered, so that’s not the issue either.
 
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The window had been raising pretty slowly for a while. I would help it along with my hands often. The gears of the window regulator and both ends of the blue cable are in good condition. So... most likely motor, transmission, or both?
 
For raising only, the power to the motor goes through a safety switch in the tailgate (you can't put the window up while the tailgate is open). That switch gets dirty over time and affects the motor performance. The switch is attached to the latch on the DS of the tailgate. Remove the screws on the latch, fish it out, disassemble the switch, clean the contacts and re-assemble.

If the motor, cable and regulator (transmission) are working at all, they are likely good. Try lubing the cable and the regulator mechanism. Make sure there is felt in the tracks. Does it work any better with the dash switch than the key switch?
 
:doah: Yes, the safety switch is on the driver’s side. TY @Blue85. Fixed it.
It sounds like you need to do some maintenance on the window first so it operates more freely. Things to check are: the track on the window where the rollers are - the grease turns solid after many years so clean it out and re-grease, I used marine bearing grease I had laying around. Check the rollers for flat spots and that they actually roll freely. Window guides - make sure they not binding the window and need adjustment. If the felt is worn then replace them. How about the felts that are in the hard top - check their condition and clean if dirty. Run a dedicated heavy gauge ground wire from the motor case to a bare metal spot on the frame. The way it’s grounded from the factory is terrible. The motor grounds through the tailgate hinges so if there’s any rust/corrosion between the hinges and tail pan the motor doesn’t get full power.
And everyone is always quick to blame a bad motor when in reality they are relatively simple and robust, not to mention you can easily disassemble and lube the bushings and clean the contacts. I don’t know how you’d check the transmission for failure and it’s a pretty expensive part to buy only to find out that’s not the issue. Been years since I’ve been inside my tailgate but you might be able to put your hand on it to feel if it’s skipping gears (just be careful - don’t want to chop any fingers off!). Or put a dowl against it and the other end to your ear - a poor man’s stethoscope.
That should keep you busy for a while. :D
 
Thanks for all the input. I will check all the things you guys listed. To get to the safety switch I need to disassemble more of the tailgate than just the access panel right?
 
MrTruck805 said:
Thanks for all the input. I will check all the things you guys listed. To get to the safety switch I need to disassemble more of the tailgate than just the access panel right?
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As Blue85 said, unscrews the 4 screws on the driver’s side latch and the switch is attached there. You can try bypassing the switch to see if that helps.
 
I have issues with my rear window too. My problem is the electrical contacts in the plug that is connected to the key switch itself are broken. Can't seem to find a replacement anywhere.
 
Getting close. I need the part that plugs onto that piece. It's part of the wire harness inside the tailgate. Has a "U" shape copper spring that makes the contact for up or down.
Thanks guys, you have given me hope that I might be able to find that part .
 
Yeah, that does look like the switch part. The lock cylinder has a little tear-drop shaped cam at the end of it that pushes one half of the "U" contact to one of the other contacts ("up" and "down" are both hots). I know I took mine apart once, cleaned the contacts and got a couple/few more years out of it. Then when it started acting up again I fabricated a new contact from some other old relay or something and that worked fine up until I pulled that gate last year.
 
The part I need plugs onto the lock switch. Its hardwired to the harness in the tailgate. Also, I believe mine has a lobe attached to the lock cylinder that makes the contact inside the plug on the harness. I tried putting solder on the contact but didn't want to melt the plastic. Its been awhile since I last looked at it, so I could be totally incorrect, especially since that lock cylinder looks so familiar. I put on a soft top so window is always down and not used anymore. I would take a picture but it's too cold and wet outside to take the tailgate apart today. I do appreciate your assistance.
 
I have a 1986 with a NEW window, regulator, channels and motor from LMC. My back window moves slow up and down. All of this installed by a glass company. And it still is sloooooow. I am puzzled.
 
Tiger5 said:
I have a 1986 with a NEW window, regulator, channels and motor from LMC. My back window moves slow up and down. All of this installed by a glass company. And it still is sloooooow. I am puzzled.
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Read post #8
 
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