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Home >> Buick >> 1976 >> Skyhawk Base, Automatic Trans >> Repair and Diagnosis >> Electrical >> Body Electrical >> Windshield Wipers - Round Motor >> Testing >> Wiper Circuits (Exc. Pulse System) >> Testing Motor (Off Car)

Testing Motor (Off Car)

  1. If wiper is inoperative, check for open relay coil, circuit breaker open, series field open, brushes sticking, defective solder joints or binding condition at relay latch arm.
  2. Motor will not shut off (rotates through 360°), check for relay coil grounding, relay latch spring disconnected or broken. Latch arm binding.
  3. Motor will not shut off (crank arm moves back and forth with a loud knock), check relay switch contacts shorting together, drive pawl spring disconnected. Motor has open shunt field and operates only in high speed.
  4. If motor has only high speed, check for an open shunt field or a poor connection at terminal "3".
  5. Motor has low speed only, check for shunt field internally grounded, shunt field lead to terminal board, BLACK wire, grounded or shorted armature.
  6. If motor has excessive speed in "HI", and "LO" speed is normal, check for an open high speed resistor or poor resistor ground.
  7. If motor stops at random and does not return to full park, check relay switch contacts. If motor operates intermittently, check for a defective circuit breaker, shorted armature or fields drawing excessive current causing circuit breaker to trip.
  8. If motor operates normal on bench, but occasionally fails on car, check for proper armature end play, gear assembly end play or poor wire connections.
Fig 1: Armature End Play Adjustment
G09323752Courtesy of GENERAL MOTORS COMPANY
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