Repairing Audi 100 Window Regulators

One of the most common problems on Type 44 Audis (1989-1991 100/200, 1990-1993 V8, 1984-1988 5000, etc.) is a failure of one or more power window regulators.

Although a dealer/stealer will almost certainly quote several hundred dollars to repair a non-functional power window, it can almost always be repaired for very little (if any) cost. Most problems with the power windows usually fall into one of three categories:

  1. Failure of the switch. This is extremely easy to test and fix with the purchase of a new or used switch.
  2. Failure of the cable in the regulator assembly. This isn't as easy to fix but you can usually repair it with a few dollars in parts.
  3. Damage inside the regulator motor. Depending on the extent of the damage, this can usually be fixed at no cost.

After talking to others, I would guess there's about a 90% chance your solution is one of the above and therefore should cost less than US$30. Most of the time, however, you can probably even do it for well under $10, if not free.

On my car, I had one switch fail in the driver's side front door. If you have to replace that switch, it's a good idea to replace any dead light bulbs while you're at it. I had a couple dead bulbs in there (on the power mirror controls) that I replaced with new bulbs from Radio Shack.

I also had the right rear window regulator fail due to problem 3 above. After dealing with this for a couple years (I didn't really have much of a need for opening the window), I finally decided to fix it.

Switch Failure

Checking for switch failure is easy if you have a multimeter. If you don't, try to borrow one, because it makes testing the switch a bit easier. You'll also need a Philips screwdriver, and, if you are testing the driver's door, a 4mm Allen wrench.

First, check the window from both the switch in the driver's door and the corresponding switch in the door with the non-functioning window. Obviously, if your problem window is the driver's window, you won't have this option. If the window works from one switch but not the other, there's a good chance it's the switch. It could also be the wiring, but this is unlikely. To check the switch, follow the following procedure:

To remove the switch in the driver's door, use a 4mm Allen wrench to loosen (about 15 turns) the screws on the underside of the armrest. You cannot remove these screws -- just loosen them. Then pull the armrest straight out and the switch assembly can easily be slid out.

To remove the switch on any other door, you need to remove the door handle. To do this, you must pull the handle out so you can unscrew the Phillips screw inside the handle. See the photo below for the location of the screw (inside the hole):

Handle screw

Now that this screw is out, you need to slide the handle assembly towards the front of the car and PULL. This is the hardest part of the whole project. I spent about 20 minutes on this door handle. I tried to do the right front and gave up after half an hour. Maybe there's a trick, but I don't get it. You need to slide the handle a little bit so the tabs don't catch and then pull out.

Once the handle is out, you can remove the switch. The loosened handle assembly (with the switch free from the assembly) can be seen below:

Handle loosened

Now you can simply unplug the switch. Test the terminals with a multimeter. With neither the up nor down half of the button pressed, check the resistance between terminals 5 and 2, and test again between terminals 3 and 1. It should be 0 ohms in both cases. Now test between 4 and 2, and again between 4 and 1, and both should be an open circuit (off-scale high ohms). Now hold down the down button. The resistance between 4 and 2 should now be 0 ohms. Now hold down the up button. The resistance between 4 and 1 should now be 0 ohms as well. The terminals are numbered; see the photo below.

Switch with numbers

If your readings don't match this, your switch might be faulty. The part number for the 1991 100 is 893 959 855. I think this might be the same for the 1989-1994 100, 1989-1991 200, 1990-1993 V8, 1995-1997 A6, 1992-1997 S4/S6, and maybe some other Audis, but I'm not sure.

If it passes all these tests, it might be useful to check that the switch is getting power in the first place. Plug the switch back in, turn on the ignition, set your multimeter to DC volts, and test between terminals 3 and 4 and again between 5 and 4. Both cases should show somewhere near 12 volts. Now hold the down button and verify that there is 12 volts between 3 and 2. Now hold the up button and verify that there is 12 volts between 3 and 1.

If your readings from the above tests are significantly different from this (like 0), your problem is probably in the wiring and will be hard to fix. But if they are right or near right (within a few volts of 12v), your problem probably lies in the regulator itself. Follow the steps below.

Cable Failure

If it's not the switch, the next thing to check for is cable failure. You might be able to verify cable failure if you hear a funny noise when raising or lowering the window. If you don't hear a noise, you'll need to continue to disassemble the door. This requires you to first finish removing the handle assembly. Disconnect the door handle cable from the door handle with the following steps:

  1. Remove the black foam from the door handle
  2. Remove the black metal clip from the end of the white (vinyl?) cable sheathing by the silver-colored metal boot
  3. Unhook the cable from the handle

A photo showing this is below:

Handle removed

Now you will need to remove the inner door skin. First remove the armrest. This is held on by two (in the back) or three (in the front) 4mm Allen screws which must be loosened about 15 turns. They can't be removed, just loosened. Once they are loosened, you should be able to pull the armrest straight off. See the photo below for the result:

Armrest removed

Now you need to remove the Phillips screw behind the handle, as pictured below:

Screw behind handle

Now remove the two Phillips screws from the top of the inner door skin in the door jams just below the base of the window. Now carefully pull the door skin off the door. It is held on by 9 or 10 clips (both black and white) that fall out easily, so try not to lose them. See the photo below for their exact locations:

Inner door skin

The door should now look something like the below photo. Remove the two white pieces of foam from the armrest supports. At your option, either remove or flip up the sound insulation. Removing it makes it easiest to work with everything, but it requires that you remove three deteriorating plastic rivet-like fasteners, which may get damaged in the process. I say keep it on for now and remove it only if you need to. I personally removed it, and slightly damaged the rivets in the process, but they still hold the insulation in place so it didn't really matter.

Inside the door

You should now be able to feel around the window regulator to see whether the cable is still intact. If it is broken, follow the directions on Chris Miller's site below. If you are not sure what you are looking for, scroll down a bit for some better photos of the regulator.

If this wasn't your problem, continue on with the diagnosis in the next section. Even if it is the cable, you might want to follow the steps below so you know how to remove the regulator to repair the cable.

If you need to replace the cable, when you take apart the regulator motor assembly, put two zip ties, one on each part of the assembly where the cable goes in, to hold the assembly together when you remove the cover. According to the Bentley manual, this will help you and is therefore a Good Thing.

Motor Failure

The next thing to check for is whether the motor failed. This requires you to remove the inner part of the door assembly to get at the regulator. At this point, I might suggest moving your car onto a softer surface (like grass) so the window is less likely to break if disaster strikes and you drop it. To remove the regulator assembly, first disconnect the door lock rod shown below:

Door lock rod

Now thread the green (or clear, depending on what color Hans und Klaus decided on the day your car was manufactured -- my car doesn't even match from door to door) door handle cable out of the inner door assembly, remove the two large hex bolts from the base of the door (one is shown below), and remove the two large hex bolts from the side of the door near the base of the window (one on each side). Be careful to make sure nothing falls and breaks the glass.

Door bolt

Now you should be able to carefully remove the top half of the door (with the window) out of the bottom half and rest it on the ground. Below are two photos taken at this stage:

Door apart from side

Door apart from back

At this point you have a choice. You can either leave the regulator in the car and work on it outside, or you can take the regulator out and work on it inside. I chose the latter, but in retrospect, it may have been better to just leave it in the car. If you want to remove it from the car, keep reading for directions. If you want to keep in the car, skip down a little bit.

It actually is easier to get at the bolts holding in the regulator if you remove them before you remove the top half of the door from the bottom half. However, as long as you have a socket wrench you shouldn't have too much of a problem removing the bolts from the regulator from the underside. But if you remove the regulator first, it may be a bit more difficult to remove the top half of the door from the bottom half.

Do it whatever way you want, but the best way would probably be to remove the three motor assembly bolts before separating the door and then remove the two bottom support bolts once the door is separated. Regardless, the bolt locations are marked below. The markings on the three motor bolts are approximate (they are easier to see from the other side), but the other two circles are exactly right.

Regulator and window assembly

Now remove the circlip connecting the window to the regulator. The two photos below first show the circlip on and then the same spot with the circlip and washer off. Once the circlip is off, the regulator should come right out.

Circlip on

Circlip off

The below two photos show the door with the regulator removed and then the regulator on its own:

Regulator removed


Now that you've removed the regulator (or not, depending on whether you took the last few steps), you need to open the motor housing. I think there's only one Phillips screw holding it on. Once you've removed the screw, carefully pull off the housing. It may be a bit stiff. See the photo below for what the motor looks like inside the housing, as well as the screw that holds it in place (no, that black plastic on the screw isn't broken -- it's supposed to be like that). I put it on newspaper so I wouldn't damage the table with any grease or other substances.

Regulator motor, top view

See how the armature and brushes of the motor have magnet fragments on them? That's why my window wasn't working -- the magnet fragments were "shorting" the magnetic field, causing the motor to not work. Clean these magnet fragments off as best as you can. Maybe try using a magnet to pick them up if your fingers can't do a sufficiently good job. See another photo below in case the magnet fragments were hard to see above:

Regulator motor, side view

Now look inside the regulator housing. You might find magnet fragments in there, too. If so, pull them out as well. If you see rust, you might want to clean that out too, but I didn't bother (I wasn't sure how exactly to clean it, since my Dremel doesn't have a long enough extension to reach in there), and I don't think it affected anything. See the photo below for what my housing looked like:

Regulator housing

You might also want to take a look at the following site for more information on cleaning the regulator motor:

The above site also has a bunch of photos that might be useful for additional perspectives, plus it has door disassembly directions for the early Type 44's (those that were called the 5000 in the US).


Now start following the steps in reverse, from whereever you left off. Put the regulator back together if you took it apart and test it. Hopefully it will work. Mine worked perfectly on the first try. If it now works, carefully follow the directions backwards to put everything back together again. If it doesn't work, you probably just need to buy a new regulator for around $100.

Last updated 2003-07-26
Eric Rechlin