Fix an inoperative Pwr Window
04-13-2010, 10:52 PM
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Fix an inoperative Pwr Window
Here is my Power Window story. About a year ago my window stopped working. I took the door panel apart, removed the motor case and rotated the armature by hand to ensure the window moved up and down freely, then I tested for voltage at the connector while pushing the switch. Everything seemed to be in order. I put the motor case back on, pushed the button, and to my suprise the window worked. So I buttoned everything up and called it a fix. WELL...it worked for three days and then quit again. So I left it for a year and just didn’t use it.
A few weeks ago I decided to work on it again. I pulled the case off the motor turned the armature, everything seemed fine, no binding whatsoever. I then inspected the electrical connector and noticed there was corrosion in it. I cleaned it with electrical contact cleaner, put the case back on the motor and again the window worked! I attributed the problem to corrosion since I had removed the connector the first time to check for voltage. BUT again it only worked for about three days!!!
I thought about this for a while and realized that both times the window started working I had turned the armature by hand. Also, before I did anything else, I held my hand on the motor while pressing the switch and I could feel it trying to turn, so I knew voltage was geting to the armature. I didn’t detect any binding in the regulator assembly so that led me to believe the motor itself must be binding. Since the bearing surfaces were fine that left the commutator and brush assembly as a possible culprit. I had an 89 Blazer that did the same thing. As the brushes wore down, the edges got very sharp and when the motor tried to turn the brushes would tilt and the sharp edges of the brushes would get caught in the groves on the commutator of the armature. On my Blazer I was able to reverse the brushes and use the new side on the other end. It worked fine for the 3 years I owned it.
Unfortunately the Corvette brushes can’t be reversed so they need to be reshaped using a file. I also cleaned up the commutator using 400 grit sandpaper. I will update this thread periodically so everyone interested will know if the fix works long term or not. Without further ado, here is the step by step procedure for tuning up a power window motor.
1. Remove the cover from behind the door pull and remove two Torx head screws.
2. Using a flat screwdriver, remove the door handle trim. Insert screwdriver into the ¼” wide slot over the handle itself and gently pry up while pulling outward on the trim piece.
3. Using a small pry bar (or an actual door panel removal tool) gently pry out on the door panel near the six mounting post locations.
4. Gently pull up on the door panel and seperate it from the door. The switch panel wiring will be connected, so remove the connector from the switch.
5. Remove the six screws holding the speaker in then remove the connector and speaker assembly.
6. Pull the plastic dust cover off the rear portion of the door.
7. Note the location of the glass mounting bolts then loosen them. The original bolt locations should be visible by the marks left on the bracket, but you could scribe a mark to make sure you get them back in their original locations.
8. Pull the glass out of the door...you may have to completely remove the bolts if the glass is stuck to the brackets.
9. Remove the three nuts behind the motor on the regulator and the connector on the motor itself. I found that the rubber seal was torn on my car and there was corrosion in the connector. I cleaned the connector and taped it up with electrical tape when I reinstalled it to keep mositure out. Hope it works!
10. Remove the four nuts holding the regulator assembly in, the lower front nut is accessed by removing the square rubber plug on the bottom of the door. Before removing the front lower nut make sure to scribe a mark so its original location is preserved.
11. Remove the regulator cable tie holding the cables to the inside of the door, then remove the entire assembly through rear access hole in the door.
12. Lay the regulator assembly down and remove four Torx screws from the back of the electric motor case and slide the case off.
13. You can turn the armature by hand to make sure it is not binding. I opened the case to make sure there were no problems with the cables or pulleys. If you don’t find any problems then procede.
14. Remove three small screws around the outside of the transmission (I’m calling the black plastic case the motor is mounted to the transmission) and carefully lift the cover off. Remove the plastic gear, this will allow you to seperate the armature and brush assembly from the transmission.
15. Using a fine bastard file whose rounded side closely matches the shape of the commutator on the armature, file the surface of both brushes. The brushes are VERY soft, you won’t need more than three or four strokes. Try to keep the surface level. Now take a small flat file and radius the edges of the brushes so the sharp edges can’t get caught in the groves on the commutator of the armature.
16. Use 400 grit sandpaper and clean up the commutator. I put my armature in a drill and held the sandpaper while spinning it. Don’t be too aggressive, just clean it up.
17. Put the brush assembly back on the armature, this may take another set of hands since the brushes are spring loaded, but it isn’t too hard if you use a small pick to hold the brushes back while sliding the armature in.
18. Now just reverse the steps and put everything back together.
A few weeks ago I decided to work on it again. I pulled the case off the motor turned the armature, everything seemed fine, no binding whatsoever. I then inspected the electrical connector and noticed there was corrosion in it. I cleaned it with electrical contact cleaner, put the case back on the motor and again the window worked! I attributed the problem to corrosion since I had removed the connector the first time to check for voltage. BUT again it only worked for about three days!!!
I thought about this for a while and realized that both times the window started working I had turned the armature by hand. Also, before I did anything else, I held my hand on the motor while pressing the switch and I could feel it trying to turn, so I knew voltage was geting to the armature. I didn’t detect any binding in the regulator assembly so that led me to believe the motor itself must be binding. Since the bearing surfaces were fine that left the commutator and brush assembly as a possible culprit. I had an 89 Blazer that did the same thing. As the brushes wore down, the edges got very sharp and when the motor tried to turn the brushes would tilt and the sharp edges of the brushes would get caught in the groves on the commutator of the armature. On my Blazer I was able to reverse the brushes and use the new side on the other end. It worked fine for the 3 years I owned it.
Unfortunately the Corvette brushes can’t be reversed so they need to be reshaped using a file. I also cleaned up the commutator using 400 grit sandpaper. I will update this thread periodically so everyone interested will know if the fix works long term or not. Without further ado, here is the step by step procedure for tuning up a power window motor.
1. Remove the cover from behind the door pull and remove two Torx head screws.
2. Using a flat screwdriver, remove the door handle trim. Insert screwdriver into the ¼” wide slot over the handle itself and gently pry up while pulling outward on the trim piece.
3. Using a small pry bar (or an actual door panel removal tool) gently pry out on the door panel near the six mounting post locations.
4. Gently pull up on the door panel and seperate it from the door. The switch panel wiring will be connected, so remove the connector from the switch.
5. Remove the six screws holding the speaker in then remove the connector and speaker assembly.
6. Pull the plastic dust cover off the rear portion of the door.
7. Note the location of the glass mounting bolts then loosen them. The original bolt locations should be visible by the marks left on the bracket, but you could scribe a mark to make sure you get them back in their original locations.
8. Pull the glass out of the door...you may have to completely remove the bolts if the glass is stuck to the brackets.
9. Remove the three nuts behind the motor on the regulator and the connector on the motor itself. I found that the rubber seal was torn on my car and there was corrosion in the connector. I cleaned the connector and taped it up with electrical tape when I reinstalled it to keep mositure out. Hope it works!
10. Remove the four nuts holding the regulator assembly in, the lower front nut is accessed by removing the square rubber plug on the bottom of the door. Before removing the front lower nut make sure to scribe a mark so its original location is preserved.
11. Remove the regulator cable tie holding the cables to the inside of the door, then remove the entire assembly through rear access hole in the door.
12. Lay the regulator assembly down and remove four Torx screws from the back of the electric motor case and slide the case off.
13. You can turn the armature by hand to make sure it is not binding. I opened the case to make sure there were no problems with the cables or pulleys. If you don’t find any problems then procede.
14. Remove three small screws around the outside of the transmission (I’m calling the black plastic case the motor is mounted to the transmission) and carefully lift the cover off. Remove the plastic gear, this will allow you to seperate the armature and brush assembly from the transmission.
15. Using a fine bastard file whose rounded side closely matches the shape of the commutator on the armature, file the surface of both brushes. The brushes are VERY soft, you won’t need more than three or four strokes. Try to keep the surface level. Now take a small flat file and radius the edges of the brushes so the sharp edges can’t get caught in the groves on the commutator of the armature.
16. Use 400 grit sandpaper and clean up the commutator. I put my armature in a drill and held the sandpaper while spinning it. Don’t be too aggressive, just clean it up.
17. Put the brush assembly back on the armature, this may take another set of hands since the brushes are spring loaded, but it isn’t too hard if you use a small pick to hold the brushes back while sliding the armature in.
18. Now just reverse the steps and put everything back together.
Last edited by JD128; 04-14-2010 at 12:10 AM.
04-14-2010, 11:33 AM
#3
Although I may never need your write-up and pictures, everyone on the forum should be grateful to people like you who take the time and trouble to convey this sort of information.
04-23-2010, 10:33 PM
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While I applaud your efforts, fortitude, and thoughts (the detailed disassembly pictures and descriptions are nicely done!), I feel something else is amiss.
I also have had the failure of the power window issue (passenger side once), and went through some trial and error tests, only to come up blank, and have had it working ever since.
As a retired electrical motor engineer, some minor issues I have with your efforts:
1. The leading edge of a carbon brush will always make contact first (assuming the brush has the correct radius that matches the commutator), since it initially is the first part of the brush to make contact. Therefore, that leading edge normally burns back a little (from being a sharp edge). So as it burns back, the leading edge tends to be further up the radius of the brush surface with a very slight chamfer at the very edge. Since these motors rotate in both directions, both edges are in effect "leading" edges. I strongly doubt that the brush leading edge catching in the commutator slots is the failure mode. It is very rare that you see a brush that has been in service for "a while" to have a sharp leading edge. The motor in those cases would be running very lightly loaded (virtually no brush arcing) for that to occur. Our power windows do not fall in that category (especially as they are run up to stall at the end of travel).
2. Use of 400 grit paper on a commutator is (or should be) overkill. A simple pencil eraser works well for removal of most light corrosion or carbon tracks (if the armature can be removed and rotated in a lathe or failing that, in a drill press). Also any "sandpaper", emory cloth, etc., can leave small bits of abrasive embedded in the relatively soft copper of the commutator, which can cause excessive brush wear and / or arcing. If the commutator has that much wear, then it should be properly cut on a lathe.
I know none of that helps in determining the final solution to our issue, and that your window continues to operate correctly (as does mine). I just hope they both stay that way. I have been waiting for mine to fail for over a year now, and it continues work........
Plasticman
I also have had the failure of the power window issue (passenger side once), and went through some trial and error tests, only to come up blank, and have had it working ever since.
As a retired electrical motor engineer, some minor issues I have with your efforts:
1. The leading edge of a carbon brush will always make contact first (assuming the brush has the correct radius that matches the commutator), since it initially is the first part of the brush to make contact. Therefore, that leading edge normally burns back a little (from being a sharp edge). So as it burns back, the leading edge tends to be further up the radius of the brush surface with a very slight chamfer at the very edge. Since these motors rotate in both directions, both edges are in effect "leading" edges. I strongly doubt that the brush leading edge catching in the commutator slots is the failure mode. It is very rare that you see a brush that has been in service for "a while" to have a sharp leading edge. The motor in those cases would be running very lightly loaded (virtually no brush arcing) for that to occur. Our power windows do not fall in that category (especially as they are run up to stall at the end of travel).
2. Use of 400 grit paper on a commutator is (or should be) overkill. A simple pencil eraser works well for removal of most light corrosion or carbon tracks (if the armature can be removed and rotated in a lathe or failing that, in a drill press). Also any "sandpaper", emory cloth, etc., can leave small bits of abrasive embedded in the relatively soft copper of the commutator, which can cause excessive brush wear and / or arcing. If the commutator has that much wear, then it should be properly cut on a lathe.
I know none of that helps in determining the final solution to our issue, and that your window continues to operate correctly (as does mine). I just hope they both stay that way. I have been waiting for mine to fail for over a year now, and it continues work........
Plasticman
04-24-2010, 08:35 AM
#12
Melting Slicks
Thanks for taking the time to put this together. I too had a passenger window that would not go down... Turned out a previous owner had tapped into the power window power supply to run some sort of aftermarket stereo setup. When I pulled his install out to go back to stock I cut his wire not knowing until I pulled the panel that I had also cut the power to the window. 
04-26-2010, 11:11 AM
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While I applaud your efforts, fortitude, and thoughts (the detailed disassembly pictures and descriptions are nicely done!), I feel something else is amiss.
I also have had the failure of the power window issue (passenger side once), and went through some trial and error tests, only to come up blank, and have had it working ever since.
As a retired electrical motor engineer, some minor issues I have with your efforts:
1. The leading edge of a carbon brush will always make contact first (assuming the brush has the correct radius that matches the commutator), since it initially is the first part of the brush to make contact. Therefore, that leading edge normally burns back a little (from being a sharp edge). So as it burns back, the leading edge tends to be further up the radius of the brush surface with a very slight chamfer at the very edge. Since these motors rotate in both directions, both edges are in effect "leading" edges. I strongly doubt that the brush leading edge catching in the commutator slots is the failure mode. It is very rare that you see a brush that has been in service for "a while" to have a sharp leading edge. The motor in those cases would be running very lightly loaded (virtually no brush arcing) for that to occur. Our power windows do not fall in that category (especially as they are run up to stall at the end of travel).
2. Use of 400 grit paper on a commutator is (or should be) overkill. A simple pencil eraser works well for removal of most light corrosion or carbon tracks (if the armature can be removed and rotated in a lathe or failing that, in a drill press). Also any "sandpaper", emory cloth, etc., can leave small bits of abrasive embedded in the relatively soft copper of the commutator, which can cause excessive brush wear and / or arcing. If the commutator has that much wear, then it should be properly cut on a lathe.
I know none of that helps in determining the final solution to our issue, and that your window continues to operate correctly (as does mine). I just hope they both stay that way. I have been waiting for mine to fail for over a year now, and it continues work........
Plasticman
I also have had the failure of the power window issue (passenger side once), and went through some trial and error tests, only to come up blank, and have had it working ever since.
As a retired electrical motor engineer, some minor issues I have with your efforts:
1. The leading edge of a carbon brush will always make contact first (assuming the brush has the correct radius that matches the commutator), since it initially is the first part of the brush to make contact. Therefore, that leading edge normally burns back a little (from being a sharp edge). So as it burns back, the leading edge tends to be further up the radius of the brush surface with a very slight chamfer at the very edge. Since these motors rotate in both directions, both edges are in effect "leading" edges. I strongly doubt that the brush leading edge catching in the commutator slots is the failure mode. It is very rare that you see a brush that has been in service for "a while" to have a sharp leading edge. The motor in those cases would be running very lightly loaded (virtually no brush arcing) for that to occur. Our power windows do not fall in that category (especially as they are run up to stall at the end of travel).
2. Use of 400 grit paper on a commutator is (or should be) overkill. A simple pencil eraser works well for removal of most light corrosion or carbon tracks (if the armature can be removed and rotated in a lathe or failing that, in a drill press). Also any "sandpaper", emory cloth, etc., can leave small bits of abrasive embedded in the relatively soft copper of the commutator, which can cause excessive brush wear and / or arcing. If the commutator has that much wear, then it should be properly cut on a lathe.
I know none of that helps in determining the final solution to our issue, and that your window continues to operate correctly (as does mine). I just hope they both stay that way. I have been waiting for mine to fail for over a year now, and it continues work........
Plasticman
In my Blazer I talked about in the original post, it absolutely was the brushes tilting and catching in the commutator. I could verify it by rotating by hand and watching it catch...and there was some damage to the commutator from this occuring.
Now in my Corvette, I couldn't see this happening...but resurfacing the brushes and commutator has the window working. Also, I don't think the brushes fit loosely enough in this motor as they did in the motor on my Blazer to tilt...it was just my theory since I had seen it before.
Here is another thought...You are right about using a pencil eraser to clean the surface of the commutator, and normally that is what I would have used. However I noticed a slight ridge just off center of where the brushes ride on the commutator. I used the sandpaper to remove that ridge. Likewise there was a corresponding grove in the brushes.
Do you think it is possible the motor could bind as a result of the motor shaft being forced forward as it hits the end of travel? If the ridge on the commutator got forced forward to slide just out from under the groove in brush, maybe that could be enough friction to keep the motor from turning.
Please add your thougts...by the way window was working this morning on my way to work!
Last edited by JD128; 04-26-2010 at 11:14 AM.
04-26-2010, 12:22 PM
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You said yours has been working since...what did you do (if anything)to fix it?
In my Blazer I talked about in the original post, it absolutely was the brushes tilting and catching in the commutator. I could verify it by rotating by hand and watching it catch...and there was some damage to the commutator from this occuring.
Now in my Corvette, I couldn't see this happening...but resurfacing the brushes and commutator has the window working. Also, I don't think the brushes fit loosely enough in this motor as they did in the motor on my Blazer to tilt...it was just my theory since I had seen it before.
Here is another thought...You are right about using a pencil eraser to clean the surface of the commutator, and normally that is what I would have used. However I noticed a slight ridge just off center of where the brushes ride on the commutator. I used the sandpaper to remove that ridge. Likewise there was a corresponding grove in the brushes.
Do you think it is possible the motor could bind as a result of the motor shaft being forced forward as it hits the end of travel? If the ridge on the commutator got forced forward to slide just out from under the groove in brush, maybe that could be enough friction to keep the motor from turning.
Please add your thougts...by the way window was working this morning on my way to work!
In my Blazer I talked about in the original post, it absolutely was the brushes tilting and catching in the commutator. I could verify it by rotating by hand and watching it catch...and there was some damage to the commutator from this occuring.
Now in my Corvette, I couldn't see this happening...but resurfacing the brushes and commutator has the window working. Also, I don't think the brushes fit loosely enough in this motor as they did in the motor on my Blazer to tilt...it was just my theory since I had seen it before.
Here is another thought...You are right about using a pencil eraser to clean the surface of the commutator, and normally that is what I would have used. However I noticed a slight ridge just off center of where the brushes ride on the commutator. I used the sandpaper to remove that ridge. Likewise there was a corresponding grove in the brushes.
Do you think it is possible the motor could bind as a result of the motor shaft being forced forward as it hits the end of travel? If the ridge on the commutator got forced forward to slide just out from under the groove in brush, maybe that could be enough friction to keep the motor from turning.
Please add your thougts...by the way window was working this morning on my way to work!
As for the commutator groove (on your C5 window motor), the motor under torque (when driving the window regulator) will be forced either forward or rearward (depending if the motor & window is going up or down). Grooving is normally a result of extended brush current wear "eating" (arcing) at the commutator. If the groove was off center to centerline of the brushes, then it says that that is where the armature is actually driving itself during one of the 2 (up or down) positions, and that it is being driven at higher than "normal" current at that point (hence the grooving). Now grooving can occur due to other causes, but that is the most likely reason.
As for the ridge causing excessive loading to jam the motor, I doubt that. An commutator type electrical motor (normally called an universal motor), unlike a gasoline engine, develops maximum torque at zero (stall) rpm. It takes a large amount of torque to stall a commutator type electrical motor. Unless the motor had failed in some way (lack of brush contact with the comm would be just one reason).
Excessive endplay can also show up and allow something else in the motor to jam (an extreme example is too much endplay allowing the worm gear on the end of the armature coupled with insufficient "gear threads, and jamming them into the driven gear teeth). Sometimes just an extra thrust washer can solve this problem (of keeping the brushes centered fore/aft) with the armature.
As for my window, I took apart the door to get at the power window motor and did some testing at the motor itself (removed the connections directly to the motor and supplied 12 VDC directly (both in up and down connections). I was getting sufficient electrical arc to indicate it was drawing good current and should of moved (but failed to actually check the amperage). The motor still refused to budge, telling me that something had either jammed / failed (similar to yours). However, it was getting late, and I had a club outing to go the next day, so I put it back together (knowing that I would be back in there "soon"). Now please know that I previously tried several other methods (as posted here on the forum) such as the hold the switch and bang the door, try the driver's side switch and bang - in multiple different areas), etc., all with complete failure. Next day going to the outing, I tried the window and it has worked ever since.................
Plasticman
06-02-2010, 01:59 PM
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UPDATE...The window on my corvette is still working as of today.
I have a 2002 Tahoe Z71, over the Memorial Day weekend the passenger side window went out
so I get to work on that one. The window is loose in the track and had to be taped up...looks like I'll be replacing the entire regulator assembly.
I have a 2002 Tahoe Z71, over the Memorial Day weekend the passenger side window went out
so I get to work on that one. The window is loose in the track and had to be taped up...looks like I'll be replacing the entire regulator assembly.
07-28-2010, 06:52 PM
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Need the transmission gear
JD absolutely a super set of clear instructions in your posting. Thanks
2004Z passenger window - I was aware of this when I purchased the car. Gear is stripped now possibly complicated with a module problem. First to repair the mechanical aspect.
Does anyone know where to obtain the nylon gear which is inside the window Motor/transmission assembly?
Mr. Chevy wants $300 for the entire motor transmission cable and runways. It appears one of previous owners had been into this and the stop adjustments are off allowing the gear to be hammered at the end of window travel.
2004Z passenger window - I was aware of this when I purchased the car. Gear is stripped now possibly complicated with a module problem. First to repair the mechanical aspect.
Does anyone know where to obtain the nylon gear which is inside the window Motor/transmission assembly?
Mr. Chevy wants $300 for the entire motor transmission cable and runways. It appears one of previous owners had been into this and the stop adjustments are off allowing the gear to be hammered at the end of window travel.
Last edited by Engdomer70; 07-28-2010 at 06:56 PM. Reason: comment on original thread
07-28-2010, 08:10 PM
#18
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here is my power window story. About a year ago my window stopped working. I took the door panel apart, removed the motor case and rotated the armature by hand to ensure the window moved up and down freely, then i tested for voltage at the connector while pushing the switch. Everything seemed to be in order. I put the motor case back on, pushed the button, and to my suprise the window worked. So i buttoned everything up and called it a fix. Well...it worked for three days and then quit again. So i left it for a year and just didn’t use it.
A few weeks ago i decided to work on it again. I pulled the case off the motor turned the armature, everything seemed fine, no binding whatsoever. I then inspected the electrical connector and noticed there was corrosion in it. I cleaned it with electrical contact cleaner, put the case back on the motor and again the window worked! I attributed the problem to corrosion since i had removed the connector the first time to check for voltage. But again it only worked for about three days!!!
I thought about this for a while and realized that both times the window started working i had turned the armature by hand. Also, before i did anything else, i held my hand on the motor while pressing the switch and i could feel it trying to turn, so i knew voltage was geting to the armature. I didn’t detect any binding in the regulator assembly so that led me to believe the motor itself must be binding. Since the bearing surfaces were fine that left the commutator and brush assembly as a possible culprit. I had an 89 blazer that did the same thing. As the brushes wore down, the edges got very sharp and when the motor tried to turn the brushes would tilt and the sharp edges of the brushes would get caught in the groves on the commutator of the armature. On my blazer i was able to reverse the brushes and use the new side on the other end. It worked fine for the 3 years i owned it.
Unfortunately the corvette brushes can’t be reversed so they need to be reshaped using a file. I also cleaned up the commutator using 400 grit sandpaper. I will update this thread periodically so everyone interested will know if the fix works long term or not. Without further ado, here is the step by step procedure for tuning up a power window motor.
1. Remove the cover from behind the door pull and remove two torx head screws.
2. Using a flat screwdriver, remove the door handle trim. Insert screwdriver into the ¼” wide slot over the handle itself and gently pry up while pulling outward on the trim piece.
3. Using a small pry bar (or an actual door panel removal tool) gently pry out on the door panel near the six mounting post locations.
4. Gently pull up on the door panel and seperate it from the door. The switch panel wiring will be connected, so remove the connector from the switch.
5. Remove the six screws holding the speaker in then remove the connector and speaker assembly.
6. Pull the plastic dust cover off the rear portion of the door.
7. Note the location of the glass mounting bolts then loosen them. The original bolt locations should be visible by the marks left on the bracket, but you could scribe a mark to make sure you get them back in their original locations.
8. Pull the glass out of the door...you may have to completely remove the bolts if the glass is stuck to the brackets.
9. Remove the three nuts behind the motor on the regulator and the connector on the motor itself. I found that the rubber seal was torn on my car and there was corrosion in the connector. I cleaned the connector and taped it up with electrical tape when i reinstalled it to keep mositure out. Hope it works!
10. Remove the four nuts holding the regulator assembly in, the lower front nut is accessed by removing the square rubber plug on the bottom of the door. Before removing the front lower nut make sure to scribe a mark so its original location is preserved.
11. Remove the regulator cable tie holding the cables to the inside of the door, then remove the entire assembly through rear access hole in the door.
12. Lay the regulator assembly down and remove four torx screws from the back of the electric motor case and slide the case off.
13. You can turn the armature by hand to make sure it is not binding. I opened the case to make sure there were no problems with the cables or pulleys. If you don’t find any problems then procede.
14. Remove three small screws around the outside of the transmission (i’m calling the black plastic case the motor is mounted to the transmission) and carefully lift the cover off. Remove the plastic gear, this will allow you to seperate the armature and brush assembly from the transmission.
15. Using a fine bastard file whose rounded side closely matches the shape of the commutator on the armature, file the surface of both brushes. The brushes are very soft, you won’t need more than three or four strokes. Try to keep the surface level. Now take a small flat file and radius the edges of the brushes so the sharp edges can’t get caught in the groves on the commutator of the armature.
16. Use 400 grit sandpaper and clean up the commutator. I put my armature in a drill and held the sandpaper while spinning it. Don’t be too aggressive, just clean it up.
17. Put the brush assembly back on the armature, this may take another set of hands since the brushes are spring loaded, but it isn’t too hard if you use a small pick to hold the brushes back while sliding the armature in.
18. Now just reverse the steps and put everything back together.
A few weeks ago i decided to work on it again. I pulled the case off the motor turned the armature, everything seemed fine, no binding whatsoever. I then inspected the electrical connector and noticed there was corrosion in it. I cleaned it with electrical contact cleaner, put the case back on the motor and again the window worked! I attributed the problem to corrosion since i had removed the connector the first time to check for voltage. But again it only worked for about three days!!!
I thought about this for a while and realized that both times the window started working i had turned the armature by hand. Also, before i did anything else, i held my hand on the motor while pressing the switch and i could feel it trying to turn, so i knew voltage was geting to the armature. I didn’t detect any binding in the regulator assembly so that led me to believe the motor itself must be binding. Since the bearing surfaces were fine that left the commutator and brush assembly as a possible culprit. I had an 89 blazer that did the same thing. As the brushes wore down, the edges got very sharp and when the motor tried to turn the brushes would tilt and the sharp edges of the brushes would get caught in the groves on the commutator of the armature. On my blazer i was able to reverse the brushes and use the new side on the other end. It worked fine for the 3 years i owned it.
Unfortunately the corvette brushes can’t be reversed so they need to be reshaped using a file. I also cleaned up the commutator using 400 grit sandpaper. I will update this thread periodically so everyone interested will know if the fix works long term or not. Without further ado, here is the step by step procedure for tuning up a power window motor.
1. Remove the cover from behind the door pull and remove two torx head screws.
2. Using a flat screwdriver, remove the door handle trim. Insert screwdriver into the ¼” wide slot over the handle itself and gently pry up while pulling outward on the trim piece.
3. Using a small pry bar (or an actual door panel removal tool) gently pry out on the door panel near the six mounting post locations.
4. Gently pull up on the door panel and seperate it from the door. The switch panel wiring will be connected, so remove the connector from the switch.
5. Remove the six screws holding the speaker in then remove the connector and speaker assembly.
6. Pull the plastic dust cover off the rear portion of the door.
7. Note the location of the glass mounting bolts then loosen them. The original bolt locations should be visible by the marks left on the bracket, but you could scribe a mark to make sure you get them back in their original locations.
8. Pull the glass out of the door...you may have to completely remove the bolts if the glass is stuck to the brackets.
9. Remove the three nuts behind the motor on the regulator and the connector on the motor itself. I found that the rubber seal was torn on my car and there was corrosion in the connector. I cleaned the connector and taped it up with electrical tape when i reinstalled it to keep mositure out. Hope it works!
10. Remove the four nuts holding the regulator assembly in, the lower front nut is accessed by removing the square rubber plug on the bottom of the door. Before removing the front lower nut make sure to scribe a mark so its original location is preserved.
11. Remove the regulator cable tie holding the cables to the inside of the door, then remove the entire assembly through rear access hole in the door.
12. Lay the regulator assembly down and remove four torx screws from the back of the electric motor case and slide the case off.
13. You can turn the armature by hand to make sure it is not binding. I opened the case to make sure there were no problems with the cables or pulleys. If you don’t find any problems then procede.
14. Remove three small screws around the outside of the transmission (i’m calling the black plastic case the motor is mounted to the transmission) and carefully lift the cover off. Remove the plastic gear, this will allow you to seperate the armature and brush assembly from the transmission.
15. Using a fine bastard file whose rounded side closely matches the shape of the commutator on the armature, file the surface of both brushes. The brushes are very soft, you won’t need more than three or four strokes. Try to keep the surface level. Now take a small flat file and radius the edges of the brushes so the sharp edges can’t get caught in the groves on the commutator of the armature.
16. Use 400 grit sandpaper and clean up the commutator. I put my armature in a drill and held the sandpaper while spinning it. Don’t be too aggressive, just clean it up.
17. Put the brush assembly back on the armature, this may take another set of hands since the brushes are spring loaded, but it isn’t too hard if you use a small pick to hold the brushes back while sliding the armature in.
18. Now just reverse the steps and put everything back together.
07-29-2010, 12:00 AM
#19
Race Director
Member Since: Nov 2000
Location: Beverly Hills (Pine Ridge) Florida
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UPDATE...The window on my corvette is still working as of today.
I have a 2002 Tahoe Z71, over the Memorial Day weekend the passenger side window went out so I get to work on that one. The window is loose in the track and had to be taped up...looks like I'll be replacing the entire regulator assembly.
I have a 2002 Tahoe Z71, over the Memorial Day weekend the passenger side window went out
so I get to work on that one. The window is loose in the track and had to be taped up...looks like I'll be replacing the entire regulator assembly.
Good luck and let us know what you find in the Tahoe.
Plasticman
07-29-2010, 12:08 AM
#20
Instructor
