Join Date: Sep 2000
Location: Washington, Michigan USA
The wiper motor in particular has a lousy ground design - it's grounded at the wiper switch (not at the motor), through a sheet metal ground strap shared with the light switch that grounds to a screw into the bottom of the instrument panel below the light switch; the black instrument panel ground wire attaches under the same screw. Make sure the ground strap is there, isn't broken, the wiper switch is tight where it sandwiches the strap, and the bottom screw is both tight and the terminal is clean. That should help the wiper motor, interior lights, and dash lights.
'69 Z28 Fathom Green