66 F-85 with rectangular wiper motor (replacement), Painless 25 circuit wiring harness. Original switch was corroded beyond saving. Replacement switch for 66 chevelle - wipers only work when washer button is held in. Read 66 CSM 12B section have tried switching the dark blue (washer ?) wire and light blue wires on the switch with no wiper action even holding in washer button. Put wires back on switch as original (and as discussed in a 2019 thread on this forum) and tried switching the dark blue and light blue wire positions between the washer and wiper motor positions without result. I measure 12V between the yellow (power) wire and the light blue wire with the wiper switch in the low position, but no wiper action. What am I missing (besides a clue)?

 

The wiper motor switches the ground side of the circuit. Try grounding the light and the dark blue wires, one should activate the wiper motor and the other the washer. You can do this at the switch and directly at the motor if it does not work at the switch.

 

^^^X2 Do you have the switch attached to a good ground or is it hanging loose from the dash while you are working on it? As said above, the switch provides ground to the motor to activate it which means the switch case needs to be grounded.

 

Thanks, will double check switch/dash grounding. The switch is in the dash and metal strap is in place. I will update the list when I get this resolved

 

Resolved problem with a new switch from Summit ( part # AWW-01993679). I had to clean up the threads on new switch so the retaining nut would thread on far enough to hold switch securely

 

Glad you got it.