Intermittent Operation (Hi & Lo)
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1990 GMC Vandura Special, 1990 GMC Vandura, 1990 GMC Rally Camper Special, 1990 GMC Rally, and 1990 GMC Magnavan. However, it is still accessible from the selected car via links, so may be relevant.
- Remove wiper fuse from fuse block and connect a 0-30 amp ammeter across fuse block terminals. Turn ignition switch to ON position. Run wiper with switch in HI position with windshield dry. Note lowest current draw reading.
- If current draw is less than 5 amps, a weak circuit breaker is indicated. Replace motor end cap assembly. If current draw exceeds 5 amps, remove wiper arms and wiper blades and repeat step 1).
- If current draw is within specification, replace wiper blades. If current draw is high, disconnect wiper linkage from crank arm and repeat step 1).
- If current draw is within specification, check wiper linkage for binding condition and repair or replace as needed. If current draw is high, problem is in wiper motor. Check for armature end play, or shorted or grounded armature.