[V6-12v] Rear Defogger Switch - 90 v. A6

Tom Christiansen tomchr at ee.washington.edu
Sat Oct 8 14:36:33 EDT 2005


DUH... You're absolutely right. Pin 3 of the switch is for the heated 
mirrors. Pin 6 is for the rear defroster. Apparently, there is a 10A 
fuse inside the switch for the mirror heaters.

Now that I'm at it: Pin 1: Instrument illumination. Pin 2: Ground. 
Pin 5: +12 V from the load reduction relay.

BTW: I saw a bulb replacement procedure somewhere. Probably on 
www.12v.org. Unfortunately, the site seems to be down (happens every 
now and then unfortunately). It could also have been at SJM 
AutoTechnik (http://www.sjmautotechnik.com/trouble_shooting/elec.html).


At 11:16 AM 10/8/2005, Eric Ragot wrote:
>Tom, doesn't the 90 also have heated mirrors? I Could have sworn I 
>was able to defrost them...
>Tom Christiansen wrote:
>>I checked the wiring diagram for my 1994 90 and you're right. The 
>>defogger switch pin 4 is indeed not connected...
>>Wonder if it could be the heated mirrors on the A6 that takes the extra pin.
>>At 09:48 AM 10/8/2005, Eric Ragot wrote:
>>>two cars of mine - 94 90s & 96 A6.
>>>the light on the 96 defogger switch does not come on when it is depressed.
>>>the 94 switch works.
>>>I pulled them out and compared - each switch has 6 pin outs. The A6 uses
>>>all 6 while the 90's switch leaves pin #4 empty.
>>>Does anyone know what the heck pin #4 is used for on the A6 and if I risk
>>>anything by using a switch that doesn't have that connector?

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