WHAT ARE THE PART NUMBERS

Original part for US-spec cars, circa 1992-1995: 441 959 257 B
European part for some cars, circa 1992-mid.1993: 441 959 257 D

I've had both parts apart and looked inside. The difference is not trivial. There are components missing from the circuit board of the -B part.

I have bought them in Europe (Italy, Germany) for prices ranging from US $120 to US $160 (the range depends on the exchange rate of the dollar and the VAT rate of the country in question) and I know that others have bought them in the US for about $200.

WHAT IS IT

This is a double wide electronic module that plugs into an aux relay panel. It controls power delivery to all the window switches, but in addition has extra connections to the driver's window, which allows the module to directly control the driver's window for one-touch operation.

WHAT ARE THE DIFFERENCES

The -B part only implements one-touch down. It implements it using a timer. The module applies power to the motor, in a downward direction, until the timer runs out, one of the front doors is opened, or the up button on the driver's window switch is operated.

The -D part implements one-touch down, but it also implements one-touch up, still using a timer. The module applies power to the motor, in an upward direction, until the timer runs out, the driver's door is opened and re-closed, the down button on the driver's window switch is operated, or the ignition is switched off.

The one-touch up feature only works as long as power is applied to terminal 61 on the -D module. There is no terminal 61 on the -B model, and terminal 61 does not appear in the wiring harness of US-spec cars. In European cars, this terminal goes to the voltage regulator output: as near as I can tell, this means that the engine has to be running for the window to go up by itself. It's not sufficient for the key to be in the "run" position, the engine really has to be running.

Since there's no wire in this terminal position for US-spec cars, we have to provide some other connection. I connected it to terminal 15, which is immediately adjacent. Terminal 15 is on with the key in "run" or "start", so in this configuration one-touch up is allowed if the key is in, even if the engine has stopped by itself for some reason. If you wanted to be more original, you could figure out where that wire wanted to be connected and go digging for it: a signal from the voltage regulator is supposedly available somewhere behind the dash. I just soldered a wire across the terminals before I plugged the relay in.

There is one other minor difference: after you turn off the ignition, the windows continue to work until the DRIVER's door ONLY is opened AND reclosed. In the original, it was either driver or front passenger, and the door merely had to be opened to turn power off. In the new one, you can open the driver's door, and the windows still work. They only stop working when you close the door.

IS IT SAFE?

Remember, it's just a timer, so if something gets in the way of the window while it's going up, it won't stop and reverse ... it'll just keep grinding away!

Perhaps it was because of safety concerns that Audi seems to have stopped using this system in Europe about mid-1993. By the 1996 model year they were using a safer system that does not rely on timers but instead gets feedback on window position from extra wires between the window regulator/motor and the controller.

WHY THIS IS NOT LIKE THE 1996 AND LATER CARS

The way that the 100/200/S4/A6/S6 (model years about 1991 to 1995) are wired, only the driver's window is cabaple of going up and down by itself. The reason is that there are no direct wires from the other window motors to the window controller -- there are always switches in between. The driver's window only has a second set of wires from the window motor to the window controller.

Starting with the 1996 model year (for the A6, for the S6, starting with the 1995.5 models), the car uses a completely different window system.

There are 6 wires from each window regulator directly to the controller. The window switches are connected only to the controller, not directly to the window motors. The controller is able, through the extra wires, to "see" the window as it's moving up or down, and by counting pulses or some such thing, keep track of the window's position. If the window stops moving before it has reached the position that the controller "knows" is the top of the travel range, the controller deduces that something is blocking the window, stops it moving, and backs it down.

A much better and safer system than the old one, but also very difficult to retrofit! Audi appears to have stopped using the old timer-based one-touch up, even in Europe, around the middle of 1993, probably for safety concerns, and they developed the new system, which we saw for the first time (in the US) about two years later.

WHERE DOES IT GET INSTALLED

On the A6/S6 family of cars, the power window module is located in the driver's footwell, just below the hood release. There's an AUX relay panel underneath there. To get to the relay panel:

Remove the trim strip in the door opening. Pry up at the edges and it pops out.
Take out the three screws that hold the bottom of the door opening trim.
The trim piece on the left side of the footwell is held in place by the lower trim piece and 1 screw. This 1 screw is near where the two trim pieces overlap. There's a cover hiding it. You can pry off the cover with a small screwdriver, then remove the screw.
Remove this left side trim piece, and pull it away from the door opening.

The AUX relay panel is revealed. The module in question is the double wide relay closest to the seat. It will probably have "329" marked on it's top.
The label side of the module is facing away from you.

The new module, -D, is marked "347". Remember to carefully solder a small wire across terminals 61 and 15 if you want to use one-touch up.

WHAT RELAY PART NUMBERS ARE USED IN WHICH CARS:

If you've read this far, here's a table showing the relay number versus year and model. There are notes about VIN ranges and sometimes equipment packages on the right. 100n means FWD. 100 without a n or Q means either, or I was too lazy to check both.

RELAY_______ ___YEARS______________   MODEL ____VIN_RANGE__________
8A0 927 826 85                       100n            >>43-F-300000
443 951 253B   86                     100n 43-G-000001>>
441 959 257D     87                   100n
441 959 257D       88                 100n            >>44-J-200099
443 959 257        88                 100n 44-J-200100>>
443 951 253B 85                       100Q
443 951 253B   8687                   100Q
443 951 253B       88                 100Q            >>44-J-200099
443 959 257        88                 100Q 44-J-200100>>
443 959 257          8990             100Q
443 959 257              91           100Q            >>44-M-050000
441 959 257D             91           100Q 4A-M-000000>>
443 959 257B             91           100Q 4A-M-000000>>            PR-4R2
441 959 257B             91           100Q 4A-M-000000>>            PR-4R3
441 959 257D               92         100
441 959 257D                 9394     100             >>4A-P-150000
443 959 257B                 9394     100 4A-R-000001>>            PR-4R2
441 959 257B                 9394     100 4A-R-000001>>            PR-4R3
441 959 257B                     95   A6

PR-4R2 is a code that means power windows from doors only.
PR-4R3 is a code that means power windows front/rear.

And here's a partial table for the 80/90 models:

443 959 257              9192         80   89-H-300001>>
441 959 257D                 9394     80              >>8C-P-300000 PR-9R2
441 959 257D                 9394     80              >>8C-R-030000 PR-9R1
443 959 257B                 9394     80   8C-R-000001>>            PR-9R2
443 959 257B                 9394     80   8C-R-030001>>            PR-9R1
443 959 257B                     95   80

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Hope there's enough info here for you to decide what you want to
do to your car.