Hi.
As I am sure many of you have had yourselves my rear windscreen wiper has packed up on my 2003 A4 (B6) Avant.
I have removed the wiper motor and it had corrosion on the connector pins.
I cleaned these off and tested the motor back in the car. No result, the motor still failed to turn.
So I have tested the voltage across pins 1 and 4 and I am getting 12 volts however this is pulsating from 0v to 12v to 0v about once every second.
I have put 9 volts across the motor, also pins 1 and 4, and have got a response from the motor. It turns as I expect it would.

Anyone offer any thoughts on why I am getting a pulsating voltage as I believe that this should be constant when the wiper is switched on?
Could this be the relay? If so which relay, where is it and anyway to test it?

Thanks
Nathan