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Author Topic: Interior: Power Window Repair  (Read 12227 times)

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Interior: Power Window Repair
« on: September 10, 2008, 17:00:00 »

Power Window Repair

Below compiled from several Farley's Forum threads is information on how to diagnose and repair power window problems. You will need to remove one or more door panels in order to service the power windows, so you should read the excellent Library topic titled: Door Panel Removal - A Door Service Tutorial by Luke Flamos (MyDodgedip), to familiarize yourself with this process.

Diagnosis and Repair

A power window problem can be caused by a fuse, a motor, a switch, or bad wires - or a
combination of these conditions.

Problem: No power windows at all

Probable cause:
  • Bad 30 amp main fuse.  Replace the fuse.
  • Defective master switch. This unit is heat molded and is NOT repairable. If one of the switches is bad, you have to replace the unit. This was a dealer only part, and is not available from the aftermarket. It may be discontinued, but you can check with dealers to see if they still have one on the shelf.
  • Bad power or ground connection to the master switch.  The master switch feeds the ground for ALL of the window motors through a black ground wire that attaches to the left metal cowl panel (per the 1987 FSM - check the Factory Service Manual for your year to be sure).  Check to make sure that the wire is properly grounded.  Also with a voltmeter, check to make sure that the harness leading to the master switch is receiving power with the ignition switch in the "ON" position. The main feed wire is tan colored for 1987 cars but it may be a different color depending on the year of your car. Check the Factory Service Manual for your year to be sure.

Problem: One or more windows do not operate, or operates sometimes. Window may only operate in one direction.

Probable cause:
  • Broken wire leading to window motor or switch. Test connections with a voltmeter to be sure.  Pull the 2 wire window motor connector first, leave the others in place. Check it with a 2 wire volt meter. It should be ground - 12 volts with the switch pushed one way, and the reverse, 12 volts - ground, with the switch pushed the other way. This is a frequent cause of many power window problems. Over time, the wires fatigue and break from the movement of the doors opening and closing. It is very difficult to fix any of the wires on the front doors because once the wires get into the car they get mixed in with a bunch of other ones in the harness, and they aren't long enough to do much with. The back doors can be unplugged from inside the car and changed. 
  • Dirty Wiring harness contacts. Carefully clean the contacts.
  • Defective master switch (Left Front door) or door switch (Left Rear, Right Rear or Right Front). As with the master switch, the door switches are not repairable and must be replaced. They were also dealer only parts and are not available from the aftermarket. They may be discontinued but you can check with dealers to see if they still them. If not, you will have to try the junkyards. You can also take a look at other model Chrysler-built cars equipped with power windows to see if the switches can be used. During the period from the late 1970s through the 1980s and even early 1990s, Chrysler was watching every nickel and used the same parts in many vehicles.  It should be noted that the switches are very much like three way light switches in your house - except that they use momentary buttons instead of toggles. Because of this configuration, if one of the switches doesn't work, the other switch for the same window won't work either.
  • Defective window motor - Window motors rarely go bad, and they will likely last longer than the wires leading to the harness plug. Window motors can be tested without removing them. To test a motor, pull the wiring harness plug and run a hot and a ground wire to it. Reverse the polarity to test the motor in the other direction. If the motor is bad, you can buy a replacement from parts houses like AutoZone. The AutoZone instructions might tell you to wire it backwards, reversing the wires in order for it to operate properly. AutoZone motors were once being sold with a lifetime warranty so check to see if they still are.  If so, it's a good deal because you can take the unit back to AutoZone for a replacement rather than taking a chance on a junkyard unit. It should be noted that the motor is NOT grounded to the body of the window regulator. The only ground that the motor receives is through the wiring harness. All grounds are fed from the master switch. The procedure to replace a window motor is listed separately in this topic.

Problem: Window motor runs but the window either moves with a jerky motion or moves slowly. It may also go down but not up.

Probable cause:
  • Defective window regulator gear or gear plugs. The procedure to replace a window regulator gear or gear plugs is listed separately in this topic.
  • Window glass is binding in the window tracks. Spray window tracks with silicone. Silicone is nasty stuff so avoid inhaling it or contact with skin. A safety mask wouldn't hurt.

Window Motor Removal

  • Warning: Window motors should only be removed from doors with an intact glass guidance system and with the glass secured in the full up position, If the regulator arm is not loaded by the weight of the glass, removing the motor will cause a sudden release of counterbalance spring energy which could result in personal injury.
  • Refer to Door Panel Removal - A Door Service Tutorial for the procedure to remove the door panel. 
  • You must prop the door glass up in the closed position in order to remove the window motor. The door glass will fall down if it is not supported when the motor is removed from the regulator. Sedge's Glass Prop Tip: "If you don't have a friend around to hold the glass you can prop it up from the inside of the door. I made a "prop rod" from a 17 inch length of a 2" x 3/4" wooden stake. This prop will also come in handy if your window motor is no longer able to hold up your glass and you can't get replacement parts right away. You can prop up the glass to keep out the weather until you get the parts. You have to be careful about driving on bumpy roads while using the prop as it might get dislodged and the glass will fall down inside the door --- ask me how I know! I painted my tool red and drilled a hole in one end so I could hang it on the wall. That way I wouldn't someday mistake it for a piece of scrap wood and throw it away while cleaning the garage."
  • Disconnect the wiring harness from the motor.
  • Remove the tie strap that secures the motor against the inner door panel. 
  • Remove the three bolts holding the motor to the regulator. Use a short socket with an extension to reach the bolts through the holes in the door panel. Tall sockets will easily bind against the metal around the door holes as you back the bolts out.
  • Remove the motor through the large access hole. Grab the motor housing only and keep your fingers away from where the motor gear contacts the regulator gear.
  • Reverse the procedure to install the motor. Torque the three bolts to 50 to 60 in.lbs.

Window Motor Gear Replacement

Power windows are moved up and down by a motor driven regulator that is counterbalanced by the
weight of the door glass.  Power window motors have a main shaft with a worm gear drive on it. The worm gear drives a flat fine toothed plastic gear that rides on a stationary shaft mounted in the gearbox body.  The fine toothed plastic gear connects to a smaller 9-toothed gear that makes contact with the window regulator sector gear. As the window regulator sector gear is rotated by the 9-tooth gear, a lift arm attached to the opposite side of the sector gear is moved either up or down. The end of the lift arm has a roller that rides inside a lift channel that attaches to the door glass. As the arm moves, the roller pushes up or pulls down on the lift channel which in turn raises or lowers the door glass. As the glass is raised or lowered, the roller rides back and forth inside the lift channel to provide smooth operation.

The plastic window motor gear assembly is designed in two pieces, so as to provide a damping effect when the window suddenly hits the top or bottom of its travel. The assembly consists of three hard nylon plastic plugs, roughly .595" diameter by .429" high, that ride inside of the fine toothed plastic gear and make contact with the flat sides of a triangle shaped drive that is connected to the 9-toothed gear.  As the window reaches the full up or down position, the plugs absorb the energy of the motor.  They are designed to be sacrificial in nature, meaning that they will destroy themselves and render the assembly useless in order to save more expensive parts like the motor worm gear or the window regulator sector gear. This design is very common in many Fords and Chrysler products built in the 1980s.

Problems with the plug type window motor gears occur when the nylon plugs age, dry out and begin to deteriorate. When this happens, the plugs no longer make positive contact with the flat sides of the triangle shaped drive that connects to the 9-toothed gear. As a result, the fine toothed plastic gear driven by the motor tries to freewheel because there is no longer a firm connection to the 9-toothed gear.

To replace the plastic inserts:

  • Remove the gearbox housing cover and seal.
  • Thoroughly clean out the old grease and bits of nylon parts from all surfaces.
  • Install new nylon inserts.
  • Lubricate the worm gear, the gearbox shaft, the area around the center hole in the seal and the center area below the 9-toothed gear that makes contact with the seal.
  • Install the gear assembly into the gearbox housing.
  • Install the gearbox housing cover and seal.
  • Warning: DO NOT INSTALL HARD INSERTS IN PLACE OF THE NYLON INSERTS. Doing so will defeat the  purpose of the plastic inserts and MAY CAUSE DAMAGE to your window motor worm gear, the removable plastic gear assembly or the window regulator sector gear.
Where to buy the plastic inserts:

The nylon inserts are inexpensive and available in the HELP section of most parts houses. The packages will usually be listed as replacement parts for Fords.  However, they will work with M-bodies as well. Some HELP packages list the size of the plugs as .595" diameter by .429" height, while other HELP packages may list the insert dimensions as 1/2" diameter (.500" by 7/16" high (.4375". Farley's Forum members have listed both sizes as being compatible with the M-body power window gear drives.

Additional Window Motor Diagnosis and Procedure Tips From Farley's Forum
member Tomline

  • With multiple problems, If the driver's door has windows that won't work, check it first. Problems in the driver’s side controls can affect drivers and passengers windows.
  • Pull the door panel slowly, it helps to sit on a milk crate. Make your goal to prevent the clips from twisting and moving around so it's easier to reinstall the door panel later.
  • Pull the 2 wire window motor connector first, leave the others in place. Check it with a 2 wire volt meter. It should be ground - 12 volts with the switch pushed one way, and the reverse, 12 volts - ground, with the switch pushed the other way. The motor works though the wires only, not by being bolted (grounded) to the car (learned that one the hard way, it ain't a horn).
  • If you pull the motor, just remove the three bolts. Use a short socket so it doesn't bind in the door holes. Be careful the window doesn't drop. Have a friend hold and lower it.
  • Mopar dealers can order new switches for like $70 for the big drivers switch, and 15$ for a non-drivers door switch. (Note: May now be NLA)
  • It's going to be the motor, switch, or wires.
  • During reassembly, take the time to wipe the big window post clean with steel wool or something. Grease it or oil it so it doesn't rust up soon. Oil the door locks and everything else too. If you have sticky rear window locks, lubricating the front ones can free up enough volt-amps that the back ones might start working again.
  • Figure on running your car battery down to the point of needing jumped during this process from having to leave the ignition on for testing. Consider the possibility of burning up a spark plug if it's buzzing constantly.
  • Hope it's not the wires. I'm not that expert, but it'll probably take an ohm-meter, and two guys with both doors apart to figure out.
  • For reassembly, tape the plastic back on the door with duct tape. Wipe it clean first so the tape will stick. If you don't put the plastic back on well, you'll freeze in the winter on the highway. Tap the panel forwards a bit to get it to fit.
  • The switches are like three way light switches in your house. Except they use momentary buttons instead of toggles.


  • Power window motor showing gears and nylon inserts - Courtesy of  Sedge
  • HELP 74410 Window regulator Gear Plugs - package of three nylon inserts - Courtesy of Sedge

« Last Edit: January 25, 2011, 13:17:41 by Reggie »
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