Join Date: Sep 2000
Location: Washington, Michigan USA
I'd say you have no ground for the motor; in typical GM fashion, the motor ground isn't at the motor - it's grounded through a little stamped sheet metal ground strap at the wiper switch that also serves the light switch - it has a pigtail on it that attaches to the metal instrument cluster reinforcement below the switch, under the same screw that attaches the instrument panel harness ground wire. Check to make sure the metal ground strap hasn't broken or corroded, the pigtail wire is still attached to it, and the other end of the pigtail is indeed under the instrument panel harness ground screw. This is shown in the A.I.M. in UPC 1, sheet B2, View "B", and in UPC 12, Sheet B2.
'69 Z28 Fathom Green