Rain Sensor - Retrofit

RobBentley

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Hi All.

Figured I would post in the A4/S4 section as all the part numbers / controllers (etc) on the A4/S4 for this are the same as on the RS4...

I'm trying to retro-fit Rain/Light Sensors & Auto-Dipping interior mirror to my B7 RS4.

The windscreen was changed to the correct one, the mirror ordered, the light switch changed to the one with the auto function and the interior courtesy harness was changed (the one that goes through the roof lining and provides all the interior roof lights, alarm sensors etc). The standard loom in the car only had plugs for installed stuff. Audi listed only one loom for the entire A4/S4/RS4 range for parts-supply so we just ordered this. This turned up with plugs for all sorts of things like the mirror, rain sensors, even a sunroof (which I don't have). I guess aftermarket its easier they just produce one loom.

Anyway - all fitted, but... and the auto lights work even without any coding! (odd..!!) there are a few problems though. They only work with the ignition on - there is no coming home / leaving home function.

A bigger problem though... the rain sensors don't work. They just work as regular intermittant...

If I code the Central Electrics controller for Rain Sensors then I get fault code:
02071 - Local Databus
57-00 - Electric Circuit Failure

If I remove the coding for the Rain/Light Sensor - this fault code will go away.

Oddly - the dipping mirror doesn't seem to show a power light (i assume it has one, a mates Golf GTi mirror looks very similar and has a light to show it has power). It's therefor like the fault is because the car cannot see the rain/light sensor...

Does anybody know if we've missed anything here? Do we need to run any wires to say a fuse in the fusebox separate to the loom we've installed? I am a little stuck now...
 
Sorry for bumping this from the dead, but I'm trying to do the same thing on my B7 A4. Were you successful in getting the rain sensor function to work?

Also, do you have the part number for the wiring harness you needed for this project? I see two possibilities: 8E1971100LC (with homelink) and 8E1971100KS (without).
 
Just make up the loom yourself, dont need to buy a complete new loom.
 
Just make up the loom yourself, dont need to buy a complete new loom.

Okay, will do! I assume this means study the wiring diagrams and get to stripping and splicing. Do you know of any guides out there, or am I basically on my own with whatever diagrams I can dig up?

thanks.
 
Yeah best & easiest way is to study schematics mate as tbh some guides online are wrong, elsawin is 99.99% correct
 
Wow, elsawin, I had no idea, what an amazing resource. Thanks for the help!

For the record, the rain sensor has three wires:
Pin 1: Wire to pin 10 of the dark brown connector at the driver's kick panel connector station
Pin 2: Wire to pin 7 of the same connector
Pin 3: Wire to ground (connection in roof harness).

I will post an update once the wiring is complete with this and other retrofits I'm doing.