GM-GMC: wipers -1997 silverado, electrical diagnostics, switch problem

Question
wipers work ocassionaly, humming sound when not working, intermitent control delay is not consistent, also wipers seem to be noisy when working ?  any ideas ?

Answer
Joe,
 
  These trucks as well as Asrto Vans and S-Trucks have a hudge problem with the circuit board/or wiper module on the wiper motor. Basicly they have bad soder connections and can be repaired by someone who knows where to look and is good with soder, or else a new board can be bought instead of the whole motor. You don't even have to go to the dealer for this part a jobber should carry it. If your truck falls in this catagory I would start there, you could still have a motor or switch problem but the circuit board is easy to access and inspect. If its not the board or there is nothing obviously wrong with it, I would start with a good wiring diagram for your truck and start by testing the powers and ground being routed to the motor by the wiper switch. If all seem to be OK you could still have a board failure or motor failure. If you are missing powers or grounds under different options(High/Low/delay etc..)Then your most likely into the switch part of the system. Some of these can be somewhat tricky so if you do take it to a shop ask around for one that is good with electrical diagnostics. Hope this helps.