I have an 89 GTI Wipers only work on high
 

My wiper only works on high. The low and intermittent won't work. I have replaced the switch a few times. Could it be a relay? Any help or advice is very appreciated.
Thanks

Is the voltage arriving on the right pins on the motor?

Could be a relay, just as you said. I should change that, easy to do and you have an direct answer.