Hello,
I am having issues with the tailgate window on my blazer. I took everything out as the window would not move before, and discovered that the inside of the transmission to the regulator was completely busted. I also had to order a new drive cable and motor as the old ones were broken.
At this point, everything but the window regulator itsself has been replaced. The new motor spins the cable but barely moves the window before stopping, however, when I use a drill everything works perfectly fine. I have lubricated everywhere that I thought could be creating friction but
have had no success. I have also confirmed that the motor is getting good voltage, about 13 volts on both the up and down contacts. The safety switch in the tailgate latch has already been bypassed. At this point I am absolutely stumped as to why the window won't function.

Basically, what is currently happening when I press the switch in either direction, the motor attempts to spin the cable and just barely moves the window. You can also watch the cable move around when the motor attempts to spin it.

Thanks in advance for any helpful tips

 

I fought with the same problem for months. I had new glass, regulator, weatherstripping, motor, wiring, and transmission. After burning up 4 motors trying all sorts of ideas I Finally ran a number 8 hot wire from battery on a 50 amp fuse to feed 2 sets of relays. 1 set for each of the 2 motors I installed along with a transmission I built to turn the cable. That's 2 motors turning one cable. Glass goes up and down now as fast and as powerful as my 2020 chevy silverado.