I have a 1989 K5, the power windows on the passenger and rear doors/ tailgate and shot. I'm able to fix the passenger but I need help with the rear. The window goes down but will not go up. I can run it up with a drill but i need to know if the motors bad. the regulator seems fine.

 

if i remember correctly the motor should have 2 wires going to it?

the motor itself grounds to the actual tailgate. so the ground should still be working if it goes up one way. try throwing direct power to either one of the 2 wires going into the motor. if it works with 12v applied in both directions then you have a bad switch or bad/broken wire somewhere

 

Thanks, do you know the easiest way to re route a new wire or should i take it somewhere. also what should i look for in the switch if its bad.

 

There is a cutout switch that will restrict the close function if the switch is not triggered. This is to prohibit the window from being opened without the tailgate being in the closed position as the glass is unsupported when not going into the channel in the hardtop. When the window gets all the way out, there is very little holding it into the tailgate.

If you can't hear the motor attempting to raise the window, then this switch is likely at fault. I believe the switch is located on the driver side of the tailgate near the top. I went out to check my spare power tailgate, but it was buried in my shed and the driver side was sitting on the ground so I couldn't get a picture of this switch.

THIS POST has the wiring schematic that should help in your diagnosis.

Of course, if the window does attempt to go up, then the cutout switch is at least passing some current through to the motor and the problem could either be a weak motor and/or some bad connections limiting the amperage supplied to the motor.

A lot of people that choose to keep the rear power window will rewire the whole thing with a pair of relays at the gate as well as a dedicated ground to the gate. The relays provide full battery power to the motor for the up & down directions without the possibility for dirty contacts in all of the various components affecting the amperage available thereby lowering the performance of the motor. The dedicated ground provides a good path to chassis ground bypassing the hinge joints that the factory wiring relied on.

 

i forgot all about that thing. whats funny is i owned 4-5 k5 blazers and that switch was either broken or bypassed on all of them

 

Any idea where a can get a Tailgate key wiring harness.mine is going out.. it has the stripped hot wire , blue wire and white wire and plugs into the back of the key hole.