How do you repair a 1994 gmc sierra 1500 wiper motor?

You Dont You Replace It. Are you sure its not the circuit board that is your problem. Some GM trucks had a recall on the wipers because the circuit board had a fracture on one of the main solder joints. Super easy to fix. Just pull off the cover of the wiper gear/motor/circuit box and take a real close look at the large solder joints. Use a magnifying glass if you have too. Then just bust out the soldering gun, touch up the fracture(small crack) and your golden.