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Tailgate window won't roll up or down

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djkonore

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Hey all, I'm new to the forum and would appreciate your help.
I recently bought a 1987 K5 Blazer (Silverado) and the rear window will not go up or down when I press the button up front. I took the tailgate cover off and connected a drill to the drive cable and it went up and down without any problems, so I thought the motor must be shot. Tried again with new motor, but still same problem. The motor is getting power because you can hear it click and see the drive cable flex but it's not turning. Also when I try the key on the outside the key will not turn either way even a tiny bit. I'm stumped and love some help from you guys.
Thanks in advance,
Conor.
 
How hard did the drill have to work to raise/lower the window? If it really struggled and/or you had to turn the clutch up really high, it may be as simple as lubing the cable to get it to spin easier. If it spun smoothly and without working the drill really hard it may be a motor issue.

Try unhooking the cable then hit the switch, does the motor turn? If so then test the voltage going to the motor when the switch is pressed. If the voltage is decent (say 8-12 with engine off) then it is likely the motor. These switches can also go bad, so if voltage is really low, or non-existant, check the switch. Keep in mind that it is heavy gauge wire that runs through that switch, and a lot of amps, so try not to ground any contacts. Check the ground wire going to the tailgate, it needs a solid ground. When in doubt, run a jumper cable directly from ground to the tailgate and see if the switch will power it both directions. If it does you have a ground issue and it should be possible to run a nice heavy gauge cable to ground on the frame from the tailgate.

The key not turning in the outside lock is possibly due to being the wrong key. The key for the doors could have been changed without changing the lock cylinder for the rear gate. Or, although it shouldn't fit at all, you are attempting to use the ignition key in the gate.
 
I tried running both the original and the new motor while disconnected from the drive cable. Both motors spun around no problem but both motors failed to turn when reconnected to the drive cable. I'll check the voltage at the tailgate and the switch tonight.
As for the key. I have an ignition key and a key for the doors. The key for the doors also fits the tailgate quite smoothly when faced downwards but will not turn at all.
 
Sounds like the cable needs to be lubed or maybe even replaced.
The key that your using for the rear window could fit and still be the wrong one.
 
Thanks guys. Anyone know where I can order the drive cable and lock cylinder, or parts in general?
 
I had the same problem check the cable as well at the part the cable goes into I can't remember what its called and lmc has just about everything you could ever need
 
Ok, so I checked the voltage at the connector that fits onto the motor and I'm getting a reading of between 11v and 12v when the dash button is pressed. The reading is the same when the button is pressed the other direction also. I took the readings with the engine off and the ignition in the on position. So, I think that rules out it being an electrical problem.
I'm currently waiting for my LMC Truck catalogue to arrive in the mail. When it does I'll order a new drive cable, the gear it goes into and a new lock cylinder (hopefully they'll have all those).
Once again, thanks for your help guys. I'll keep you updated on my progress with it.
 
There is a safety switch in the tailgate that stops the window from moving when the gate is down. It's WAY up inside on the driver's side.
Pull out the drivers latch on the tailgate and you see the switch.
By pass that switch and I'm 99% sure your window will work.
They corrode inside and kills the power for up or down.
 
Irish1941 said:
There is a safety switch in the tailgate that stops the window from moving when the gate is down. It's WAY up inside on the driver's side.
Pull out the drivers latch on the tailgate and you see the switch.
By pass that switch and I'm 99% sure your window will work.
They corrode inside and kills the power for up or down.
Click to expand...

I was kinda thinking this too. If you can bypass the switch, it seems to also get more solid power. I just reached in, unplugged it, placed a jumper wire between the two connections and done. (I also taped it good too) :waytogo:
 
That's it.
If I recall correctly, should only be a wire in and a wire out. Switch grounds out to the gate so no ground wire.
Been a while since I fixed one.
 
I just tried running 2 wires directly to the motor from the connector between the tailgate and the truck frame. That didn't work either. It does get power because the drive cable stiffens for a second and makes a click sound when I press the switch, just like it did all along. But it won't turn the cable.
 
Hmm...I see now what you're saying.
Motors spins jumped directly but won't spin the cable...so motor is working.
And the cable isn't broken because goes up and down on the drill

Lube the crap out of the cable.
Take the cable right out of the gate.
The grease gets old and stiff in the cable. It's just like a speedo cable.
Can you spin the cable with your fingers once you got it out?
Looking at one right now. Grease looks like mud and about as thick.
Problem is the inner cable won't come out for a proper lube.
Hard to explain but you'll need to get lube directly into the black cable housing.
Spray lube can't get past the white fittings on the ends. Slide up the white fitting and spray directly into the black cable housing.
 
So i rolled up the window for the night using the drill again. Right after that I put my hand around the drive cable near the middle and noticed that it was very warm. I guess there is too much friction inside the cable. I think I'd better go ahead and order a new one.
 
Yep, sounds like a cable problem but it could also be the 'transmission' that the cable runs to on the regulator. LMC has all the parts you need, but remember that the lock cylinder will usually need to be keyed, so take it to a lock smith with your door key and they should be able to match it to the doors.

That safety switch, for those that don't know, only affects the up side of the window. The window can still be rolled down if that switch is bad or good, since it was designed to prevent someone from closing the tailgate with the window up.
 
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