Window Switch Bulbs
1. Remove switch assembly from armrest or door panel. This process varies with the door, and is roughly outlined in the relevant Bentley. For front doors, the lower armrest cover is removed by a screw or two, then the now revealed screws removed, the upper panel slid rearward a tad, and then weaseled upward, taking care not to damage the leather. The electrical connector to the switch is removed, and the switch itself removed by applying pressure to the tangs holding it to the panel.
2. Unlike the seat heater control, or remote mirror control, for example, the window switch base (where the connector pins are) does not have exposed protrusions for locking the base to the cover (the black plastic covering the switch sides). Instead of being exposed through slots in the switch cover they lock into the cover internally, four places. Before trying to release them, an additional step is needed. The actuating lever must be removed. Examine the actuating lever assembly (the part one actuates the switch with). It will be seen to pivot at its center. The lever has two axial protrusions that snap into holes in extension tabs that are part of the switch base. Carefully pry out one side, say right, of the cover at the lever end while pushing the lever to the left. Pull up on the lever. It should come out of one pivot hole. Then it can be pried from the other pivot hole.
3. Removal of the lever will expose a clear plastic covered area, below which is the light emitting diode (LED) that has failed. It will also expose four extensions of the brown colored switch base. Two are the pivot points described above. Two at the other sides are locating pins and are used to push the base out from the cover. To accomplish this, tools such as jeweler's screwdrivers are used around the base to release the base protrusions from the slots in the side cover. Using your 6 hands, wiggle and push until the base begins to slide out. Then the locating pins can be further pushed until the switch is apart.
4. Clean the transparent plastic of any plastic chips that resulted from the preceding process. Clean out historical spilled substances from the parts, if applicable.
5. The LED is a T1 size, and can be replaced by a same size one from Radio Shack (don't have the number handy, but my Radio Shack store had only one type of this size, a package with two LEDs, rated for 10 mA nominal, 20 mA absolute maximum). In the switch I just repaired, the LED was in series with a 270 ohm resistor. This would allow 50 mA to flow with 13.5 volts across the switch. I don't know if this was a fabrication error or Audi uses particularly robust LEDs (evidently not given their propensity to fail), but for the new Radio Shack lamp, a larger resistance is called for. Replace the resistor with a 1 kohm 0.25W resistor, or thereabouts (up to 1500 ohms would be fine).
6. Replace the LED, taking into account that the long lead is to be positive and goes to switch pin 4 (the center one) whilst the shorter lead goes to the resistor (which ultimately goes to ground after a tortuous path through the switches and control unit). The LED is easily damaged by stress on its leads, so plan and bend before soldering. Use an iron that is not so hot that it smokes the solder rosin. Install the LED so it is in the center of the appropriate switch section. (Check with the cover portion to ensure proper alignment in all three axes.) Make sure the solder flows properly and forms a fillet that is indicative of a noncold solder joint. Check that the two lever extension pieces that slide in the base assembly are still free to move. *** Avoid using the soldering iron tip to reconfigure the plastic parts. ***
7. This would be a good time to use some CAIG ProGold or DeoxIT on the switch contacts, if available. Given the high currents that flow to the window motor, this is not critical.
8. As the Bentley says, assembly is the reverse of removal.
