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Window motor rebuild - How to

33157 Views 73 Replies 31 Participants Last post by  chevymaher
Well I guess I'm the first to discover this, so I'm going to try my hand at making a 'how to' on it. Here goes.

It's pretty common to see people having issues with their power window motors, but now I know why. There is a resistor built into the motor unit, in series with the motor istelf. This is a temperature dependent resistor, where the temperature is determined by the current flowing through it. As the temperature increases, the resistance increases, allowing less current to flow. The problem is, these seem to get more sensitive as they age, resulting in the quite common "Motor stops working and I have to wait to use it again" issue.

All you have to do is bypass the resistor.

First of all, you'll need to get the motor out of the door. Follow your standard trim panel removal procedure (I use a crowbar) to get the trim off, and use a metal drill bit to drill out the rivets holding the motor in. You'll want to put some duct tape running up one side of the window, over the door frame, and down the other. This will keep the window from falling into the door when you take the motor out.

When you have the motor out, you'll need to crack it open. There are three metal tabs that hold on the plastic end cap, I found that a pair of large channel locks worked quite well for bending these.

Then carefully pry off the end cap. The whole thing will most likely be covered in a very sticky grease (marine grease?) that will give you some trouble in getting the cap off. Be aware that the motors brushes are attached to this cap and are under spring tension, so be patient and take your time if you don't want them to fly in all directions when you finally get it off.

Once you've finally removed it, the underside should look something like this:

That copper bar there with the numbers on it is the culprit. All you gotta do is put a dab of solder where the top bar is exposed to the bottom bar:

And just like that, it's fixed. But now comes the hard part: getting the motor back together. Initially I had tried to stick the stator back into the end cap with the brushes, and then stick all that back into the housing. I quickly found out though that the magnets on this thing are quite strong, and will just yank the stator straight out of the brushes. I did find an easier way though. Start by bending all the rear tabs on the brush mounts all the way out. Initially they should look kinda like this:

And you want them to look like this:

Now, you want to pull the stator out only enough to attach the brushes and end cap. But again you'll find that the magnets just want to yank the stator back down. What I did was I took a couple of flat iron bars (from a scrapped transformer) and stuck them down the sides of the housing, where there are gaps between the magnets. This was enough to hold the stator up, and I was able to remove them without disturbing the endcap.

Now you'll need to put the brushes back in. With the stator still pushed up and the end cap sitting on top, push the brushes through the backs of the brush holders. The brushes have a 45 degree cut on two sides, these sides need to go against the plastic end cap. Now put the springs in, and take a pair of pliers and start squeezing the end tabs together, just enough to put some tension on the spring. Push the spring towards the stator to make sure it is in all the way, and finish bending the end tabs back to their original position.

Remove whatever you used to hold the stator up (being careful not to dislodge the endcap), and push the end cap back down to its original place. Then bend the metal tabs back, and you're done!

It should be noted that this resistor was most likely a safety feature, cutting power to the motor when it was unable to move. This fix is done at your own risk.
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I have just completed the impossible corbonite maneuver.Whoever was involved in this thread they are Da Man.I was ask to go to the store.Got in the van.Humm window went up an inch and stopped.That's new.Well on the way to the store in the cold' it went up a inch at a time every couple minutes.Well I am stressed my baby is ill.Then I had a passing thought.
can't fix stupid.jpg

I remembered this thread and started studyin up Jethro Bodin style.
Well after grumbling about the door panels being impossible to get off without hurting them, I went for it.Only thing I did different was took out the stator assembly to get the brushes back on.Held the stator assembly with a pick while I fought the magnetic forces getting it back into the magnets.
I used Mass air flow cleaner on all the connections and brushes.Soldered that breaker joint.And greased the inside of the motor and the moving parts of the window track.Got it together and I was singing hallelujah.Works like brand new.Saved myself a heap of dough on a window motor Reckonin while I transpired. :character-willie:
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Yes it was a bi-metal strip thermal disconnect.Corroded high resistance across the connection.Brushes were full of burnt grease also causing bad contact,due to brushes not extending correctly.In turn the motor was drawing to much current due to the resistance causing it to open almost immediately.As long as the window moves overheating is not an issue.If the window locks/hangs up then you have a overheating issue.Fix the window track and don't lay on the button.Brushes next in line to wear out now.They were about half worn.
I was doing follow up homework on the window bi-metal strip over-ride in this thread.Due to concerns of burning things up.On the fuse panel with all the other fuses, there is a breaker for the electric windows.So it is still protected.Blow that one they both go out.
RECox286 said:
Hey CM,

You have to take into account that the auto reset c/b that comes with the truck is sized so that both windows will work at the

same time. When one of the window thermal switches opens, and since the c/b has not tripped, the other window will still work.

That is why I advocated a manual reset c/b sized to trip at slightly more than what the T/S is set for. (If that makes any sense.)

Yes I considering all possibilities.I am considering the breaker in the motor itself is to protect the windings which are more fragile than the van wiring.Seeing as the motor is not serviceable unless this procedure is done,that is a mute point.The wiring is protected by the breaker.That is my theory at this point.I wish my 90 van was still around I would go directly short the wires and hit the button see what really going on.Yes a in line fuse would be a good idea.What value would it be? With out having a guinea pig like my old 90 would have been.A guess is as usless as nothing if your wrong. The original poster never had a problem he messaged me.I have not so far.So I guess we the guinea pigs.Really if I had the value I needed I more than willing to put it in.I still working on it looking for the bi-metal switch value.I hear ya and I ain't thrown in the towel just yet.
Seems reasonable on the ratings. Same things my brother an electrical engineer tells me.

But since we here again. I will give the hillbilly weather out the window report on mine.

Since feb we have discerned 2 things.

1 window still works like new.
2 Van hasn't caught fire yet.
A Random Bush said:
Great Tutorial! I'm going to go do this right now on my '93 astro :D
One question do I get this damn thing off?
What off? the motor.
Got to put a piece of wood in there to hold the window up.
So it don't fall and possibly break, or slam your hand in there when your unawares.
Drill the pop rivets out. After you get in so far they spin.
Got to hold the drill bit at a 45 degree angle or so and let it chew the end off till it comes off.
I used a nut and bolt to replace it. Makes it simpler in the future to work on.
I said I was going to do a circuit breaker to platicate the Nay-Sayers.
I had no intention of doing so because it has one in the fuse box already.
I roll my window down everytime I park it in the garage. So I can reach in when it down there.
I got 2 years in feb on my window motor rejuvination. Works like new still and I never had any problem. Even after having that side wiped out last year. I put that motor and track in the new door and it runs like a swiss watch. I thinking the redundant circuit breakers were not needed.
There is another breaker in the fuse box for it. I did mine over 5 years ago. Nothing caught fire yet. The apocalypse hasn't come to pass. Window just works.
Well in 8 years the earths axis hasn't changed and the van hasn't caught fire yet. It is time to do the passenger side finally. Door has a rattle and the door panel got to come off anyway. Eliminate this breaker and new door handle time.
Man.... I think I'll just buy a new motor🙃. Bad enough taking the panels off. I mean there's just some things I'll leave to the professional window guy,like you guys. 😁
It is a pain. I did drivers side it still is perfect after all these years. Van never burned down as the nay sayers predicted. The passenger has needed it for about 6 years. But it is such a pain I never did it. New motor or rebuild the old one.
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