Here is the working solution to Audi A4 electrical windows not working problem. Help it helps when Audi drivers have the same issue.
Audi A4 avant 2003
I have a problem with electrical windows not working on A4 avant 2003 year (front doors electrical only).
So far I checked wiring on doors (ok), motor works (for windows movement), switch for up &down works (it is ok), no DTC on VAG diagnostic scanner, fuses checked &ok. The electronics in the door get 2x +12v, ground is also there…
Everything else on the doors work- central locking, mirrors, all work. Just windows don’t go up or down.
There is no message in cluster. I also checked the pcb of the “door control module”. Looked ok (soldering &stuff) but i didn‘t test the 3 relays that are on pcb.
Any ideas where else to look?
1. Maybe check convenience module under passenger floor? Very common to get water damage!
2. One relay inside is faulty.
1. Based on possible reason 1. to check if there is water damage
So like suggested, I checked the Central control module under the carpet (driver side LHD). There was no water damage, wires ok. I even re-soldered the pins on the pcb (some looked bad) but it didnt help also.
So after some more googling and measuring in the car I found somewhere with the same problem and the solution in the end was replacing the Central electronics module. I got an used one today, replaced it and guess what… windows work!
No idea what is wrong with the old one..just happy the “new” one works.
2. Based on possible reason 2. check all relays
I tested all relays today and you are right. 1 relay is faulty (1 coil out of 2 isn’t working). Will replace it with a new one tomorrow and test it on the car this weekend (I guess) and report later.
I changed the faulty relay and the windows work (move) again
You can see the faulty relay in the picture in the attachment (marked with a square)- maybe it can help someone in the future.
BTW… if you test the relays on the pcb… use the instrument (to measure the conductivity of the relay coil). Do NOT put 12V power and GND to try the relay coil (it will break the small transistors that trigger the relay coil).