I have a windshield wiper timer problem sometimes I put the windshield wiper on the first position it should make one pass and wait a while for however many seconds then another pass but sometimes it stays on for 5 are ten minutes then cuts off ,is there somethingI can do about this problem,maybe somethinglike clean a contactor somewhere are something.Thanks its a 2003 Sierra 4.3l extended cab

 

The wiper module is likely corroded from water intrusion...its under the cowling..

 

Thanks Argon as soon as I find out where is the cowling I will try to locate it thanks again for your reply and time.

 

Remove the wiper arms..and the cowling is the black plastic piece that hides the wiper linkages...remove that...and a metal shield under there...then you'll see the wiper motor.
The module is also the wiper motor "cover"

 

Thanks very much Argon for all your help