Wiper motor not working

Hi , I am new to this forum, I have a 2004 golf 1.9 TDi , wipers not working. I am trying to find out the correct way to test the motor, I have 3 wires, I have a perminant feed 12volts ?, I have an earth wire? The 3rd wire, comes from the Body control module and is spliced to a rain sensor if fitted. Now this wire must be the wire to switch the wiper motor on, I can’t find any information as to what this wire should read when the wipers are called for, a voltage? A can signal, etc, normallly if you give a motor a live and a earth it will run, but on this 3 rd wire it must switch something in side of the motor electrics to turn the motor on, I was thinking of giving the 3rd wire a12volt feed to see if ot works , but I don’t know if I am going to do any damage.
I would be very great full if any could explain the correct action required to diagnose this problem.


Thanks

Paul