On my 3rd A4! RS4 next???
I used the following when I did mine.
No loom but its just 2 wires - 1 earth and the other to the dash. Not sure which pin.
Hope you get sorted.
Just fitted the washer sensor yesterday and it was not too tricky!
1. Remove passenger front wheel
2. Remove wheel arch liner completely
3. Hole for sensor is located at base of reservoir, should be plugged, remove plug and allow to drain.
3. Used Spade terminals to connect wire to sensor, (I used speaker type wire so both ends will be run into cabin)
4. Seal the connections using silicon to ensure no water ingress and rout cable though top of wheel arch.
5. There as a large grommet to the right of the suspension that already has a large cable going through with a small "nipple" above and below where the cable goes through. Snip the end off and feed the cable through.
6. Inside the car I removed the glovebox to gain access to the grommet which ou should hopefully see the cable sticking through. (left of the blower housing)
7. Pull all excess cable through before refitting the inner arch cover and replacing wheel. (Check for leaks first!)
8. Route twin cable to drivers side and run one end to earth and the other to pin one behind the speedo as described earlier in the posts!
9. Put all the car together again and hey presto no warning light ( So long as you have filled with water!!)
Hope this is of use to someone! Let us know if you have any problems. Takes about 1 hour in all and you will need a torx screwdriver for the screws that hold the arch lining in and an 8mm socket to remove the glovebox!