My 1990 K5 is having major issues with the rear window. It won't go up anymore, the motor doesn't even try to lift it from the switch inside or the key hole on the tailgate. Also, the tailgate doesn't open, it seems stuck but thats a different issue. The window wont go down either, the motor will just rev. What should I do? All help is greatly appreciated. Thanks.

 

Sounds like there is a combination of problems. You may have a problem with wiring and/or the actual drive cable from the electric motor to the window regulator. You can access the motor and drive cable by removing the access panel on the inside of the tail gate.

Another thing is that the motors in these tailgates are known to go bad and they are expensive to replace. I am going to a power rear window in my '74, but you can bet that I'll be keeping the manual parts just in case.

Once you are in there, test the wiring at the motor for proper +12V when you hit either up or down.

You must fully lower the window to be able to open the tail gate. You can do this by disconnecting the drive cable from the motor and connecting up a drill to it. This will allow you to operate the window so long as the drive cable is still operating properly.

 

The access panel is off. I'm assuming the drive cable is the blue wire going to the motor? It is very loose and a little clamp fell off of it. Now the window motor doesn't even attempt to lower or raise it. When you turn the key to lower it, it just clicks and that's it. I have to use brute force to close the window and then put wood below it to keep it closed. I would try what you suggested but I don't really follow. Thanks for the help though

 

I guess at this point you have to decide if you can fix this yourself. You sound a little unsure of yourself.

Here are some pictures of the window regulator and the drive cable that you will find inside the tailgate:


If the window will not stay where it is, then it has become disconnected from the regulator, or the regulator drive transmission (where the blue cable attaches) is faulty.

Either way, you need to get the tailgate open. Down at the bottom there will be a lever that the window hits when it gets to the lowered position. This unlocks the latch to open the tailgate. You should be able to push down on the lever and then open the tailgate. Before doing so, you need to make preparations to support the window or you may break it.

Once you get the tailgate down, you can either remove the window, or support it on something while you work inside the tailgate. If the window is disconnected from the regulator like it sounds like it is, then you should be able to unbolt the regulator and remove it.

Before you go through all of this though, if this is your daily driver, you may want to try to find a replacement regulator so you can fix it all and be on your way.

 

It's not my daily driver, it's just something that I like to mess around with every now and then. The window regulator in those pictures seems to be jammed because it will not move for me. Is there anything I can do to force the window back onto the regulator or force it to move? It's raining a lot here and I'd like to get this darn window back up.

 

My advice would be to remove it and see what you can do with it outside the vehicle. The gear section of the regulator could be bent up or there could be something jammed into that or the transmission.

DO NOT take the regulator itself apart. That coil spring is strong! At most, pull off the transmission, but make sure you have the regulator in the all the way up position or the arms may snap to that position against the spring. It's held in with 3 bolts onto the main regulator frame. Clean things up and assess what may be wrong.

 

I think the gear is jammed; like I said earlier, It Will not move. I Will try to force it to move by pushing on the metal bars that the window sits on. Can you tell me why the motor runs when I turn the key to the lower the window, but when I Ttyl to raise it, It doesn't do anything?

 

You cannot move it by pressing on the arms when the transmission is installed. It just is not possible. To manually move the regulator, you have to turn the transmission drive.

It is possible there is a wiring problem for the down operation of the window. See the attached wiring diagrams for the power windows in your truck (as well as the Suburban). The diagram you are concerned with is located in the upper right.

 

There is a blue wire going from the gears to the motor, I dissconected the wire from the motor, but the the side that is attached to the gears isn't so easy to detatch. If I remove this cable, then can I move the regulator arms?

 

No. You have to turn the cable. Try it. See if the arms move when you turn the cable.