How-to: Window regulator replacement

For the past year or so the drivers side window on our '99 Montana was sluggish and came up crooked and eventually needed manual assistance to get it back up. It got to the point that we stopped using drive-thru's (Tim Hortons ;) ,etc..) to avoid the aggravation of struggling with it. I tried some of the 'patch' fixes that I read about on the forums like lubricating the guides with silicon oil and making internal adjustments but they resulted in mild temporary improvements at best. The real problem was that the window regulator assembly was worn out.

I was recently quoted $400 by a local body shop to fix it so I decided to try it myself. I ordered the replacement regulator from a vendor off eBay for $22 with free shipping (Oct. 08). This is the scissor type of regulator as opposed to the cable type that my GTP uses. It looks to be about the same quality as the original so I expect it to last for another 9 years :) It also came with a replacement front vertical window guide/U-channel but I didn't replace that since mine is still in great shape.

The job was not as intimidating as I envisioned. I wasn't smart enough to take pictures as I went (greasy hands + I just wanted to get the job done) so I will attempt to describe it here in as much detail as possible as I best recall.

Here we go:

Remove the door panel:
- Remove the two 10mm bolts near the inside door lever. One of the bolts is hidden by a cup shaped cover that pops off with a little persuasion by a small slot screwdriver.
- Carefully pry up the lock/window/sideview mirror switch panel also using a slot screwdriver.
- Unplug the 3 connectors from the back of the switch panel (press locking tabs in before pulling). Put the switch panel aside.
- Pull the door panel away from the metal frame of the door. The panel is held on using plastic anchors. Use a large slot screwdriver to help pop the anchors out of their holes.
- Lift the door panel up and away from the frame. You'll have to pull on the latch handle in order to get the panel off. Put the panel aside.
- Remove the protective plastic. Don't worry if the black tar-like adhesive stays on the metalwork or comes with the plastic. Put the plastic aside, adhesive side up.

Remove the glass:
You need to position the window so that you can access the clamps that hold the glass onto the horizontal guide of the window regulator. Assuming your power window still somewhat works:
- Plug the power window harness back into the appropriate socket on the switch panel. Turn the key to the run position and put the window 1/3 of the way down so that you can access the plastic clamps that grip the glass. If your window doesn't work at all then you need to manually position the glass so that the clamps are exposed.
- Once the clamps are exposed, have an assistant push in on the plastic locking tabs while you slide the window out of the aluminum clamps. Be sure to hold onto the glass to prevent it from falling down or out.
- Pop the rubber/felt weatherstripping off the inside of the inside bottom of the window frame.
- You should now be able to manoeuvre the glass out of the door frame from where it usually sits by tilting it forward or backward, whatever allows you to pull it up and out of the window opening through the slot where it normally moves up and down. Put the glass somewhere safe for now.

Remove the Plastic Frame assembly:
- Unplug the power window harness from the switch panel and put it aside.
- Unplug the speaker and all other visible electrical plugs from the inner plastic frame. Remember where they came from. Most will only reach one mating socket so you shouldn't have much trouble so long as you remember to plug *everything* back in while you reassemble.
- Free up the wire harnesses that are interleaved in embedded clips across the plastic frame.
- Unclip the 2 pushrod linkages for the door latch and door lock from the embedded guides in the plastic frame.
- Carefully remove the lock/latch lever mechanism from the plastic frame with the help of a slot screwdriver. Pop the bottom pivot out first then the whole assembly will slide out.
- Remove all of the 10mm bolts that hold the plastic frame into place. Hold onto the frame when undoing the last bolt to prevent it from falling.
- Manoeuvre the plastic frame out from the metalwork of the door making sure not to get caught up on the wire harnesses and door latch/lock linkages.
- You may need to unplug more harnesses that weren't accessible earlier.

Regulator disassembly:
- Plug the power window harness into the appropriate connector on the switch panel and plug the motor back in.
- Toggle the switch to "wind" the window UP. The sector gear of the window regulator should disengage itself from the pinion gear on the motor.
- Once again, unplug the power window plug from the switch panel and put it aside. Unplug the motor harness.
- Place the plastic frame & regulator assy on a flat surface.
- Locate the adjuster locking stud that protrudes through the plastic frame from one of the regulator arms and remove the nut.
- Note the position of the inner end of the spring in the metal pivot then remove the spring using a pair of vise grips by unhooking it from the plastic post. There isn't a lot of tension on the spring when the window is in the up position so there's little chance of encountering a dangerous projectile like there is when attempting to wind a garage door spring :)
- Use a pair of pliers or vise grips to twist the metal pivot about 1/4 turn to release the regulator assembly. The regulator is on its own at this point.
- Remove the aluminum U-channel that clamps the glass from the old regulator assembly and install it onto the new assembly. Notice that both ends of the U channel are bent in to prevent the sliders from falling out the ends. Carefully bend the metal straight to allow the sliders to come out.
- Install the U-channel onto the new regulator assembly. Make sure both sliders move freely without binding. Carefully bend the ends in as they were before.
- Install the new regulator assembly onto the plastic frame. The metal pivot should snap into place at about 1/4 turn.
- Turn the assembly over and re-install the spring. Position the scissor regulator so that the slot on the metal pivot is in the same position that it was when you removed the spring. You may need to use vise grips to stretch and hook the spring onto its' plastic post.
- Install the nut back onto the adjuster stud that protrudes through the plastic frame from one of the regulator arms. Hand tighten it halfway up the adjustment slot for now. Final adjustment is made after the assembly and glass are re-installed.
- Plug the window switch and motor harnesses in. Toggle the switch down and carefully mesh the sector gear into the pinion gear on the motor until the pinion is about half up the arc of the sector gear. Be careful not to get your hands caught up in any of the mechanism while doing this.

At this point have a look inside the metalwork of the door and make sure the rubber/felt guides are in place of both vertical U-channels inside the door.

Re-assemble everything in the reverse order. Remember to route the wiring harnesses through the guides in the plastic frame. Be careful not to pinch any wires when you bolt the plastic mechanism back into place and make sure to plug all harness connectors back into their corresponding sockets. You don't want to have to take everything all apart again to plug one of them in !

When re-installing the glass feed it back through the slot in the door making sure to carefully line it up into the vertical rubber/felt lined guides on the sides of the window opening. You'll need to temporarily connect the power window switch so that the regulator can be positioned with the window clamps exposed in the framework so that the sliders in the horizontal U-channel can be snapped back into the plastic clamps that grip the glass.

Fine positioning of the regulator can be performed by loosening the nut and moving the slotted adjuster for smooth operation and final resting positions at full up & down. Some adjustment for smooth operation can also be made by bending the rubber/felt lined guides inside the door. Tighten everything up when you're happy with it.

Hope this helps.
Hugh "Radeohedca".
Waterdown, Ontario.

Fantastic How-to Radeohedca:biggrin: Saved me hundreds of dollars, the directions that came with the $24 regulator were useless, and made the job sound much worse than it was.

One very small detail, a mistake I made that perhaps others won't have to.
"Once the clamps are exposed, have an assistant push in on the plastic locking tabs while you slide the window out of the aluminum clamps. Be sure to hold onto the glass to prevent it from falling down or out."

I thought slide the window out meant up and out, but really you meant sideways. Having just completed this repair I would recommend holding down the tabs and tapping the aluminum bar sideways to the right. Once this is done the window will lift up easily.

With the *new* plastic window insultors I bought for $7 (gm part# 15786626) to replace the ones I destroyed on the dissasembly process, the glass goes back down into the aluminum bracket, then I gently tapped the aluminum bar to the left to latch the windows insulators into position.

The dealership wanted over $800 for this repair, my cost $32.

Fantastic How-to Radeohedca:biggrin: Saved me hundreds of dollars, the directions that came with the $24 regulator were useless, and made the job sound much worse than it was.

One very small detail, a mistake I made that perhaps others won't have to.
"Once the clamps are exposed, have an assistant push in on the plastic locking tabs while you slide the window out of the aluminum clamps. Be sure to hold onto the glass to prevent it from falling down or out."

I thought slide the window out meant up and out, but really you meant sideways. Having just completed this repair I would recommend holding down the tabs and tapping the aluminum bar sideways to the left. Once this is done the window will lift up easily.

With the *new* plastic window insultors I bought for $7 (gm part# 15786626) to replace the ones I destroyed on the dissasembly process, the glass goes back down into the aluminum bracket, then I gently tapped the aluminum bar to the left to latch the windows insulators into position.

The dealership wanted over $800 for this repair, my cost $32.