I am restoring a 75 Vette and I am having trouble with the wipers. I have read most of the information on them, but still don't understand how they work, and therefore why they don't work. There is power to the middle (yellow) wire at the motor. The ground to the motor housing is good. Do the other two wires create a second ground thru the dash switch? I pulled the motor out of the car and it works if I bypass the internal circuit/switch. There are two wires running to the motor one forward, one reverse that is different. There are 3 leads into the circuit/switch; one runs the motor in reverse, wiper parking circuit? The other two do nothing. What are they supposed to do? High and low? If that internal switch is bad, can I get it separately?

 

The 3 prong connector on the motor:
Top=Green=is a ground to make the wipers run on Low speed.

Center=Yellow=is hot with the key ON.

Bottom=Black=is another ground to make the wipers run on HIGH speed.

There is also a seperate long black wire on the motor that connects to a bolt on the bellhousing.

The switch on the dash has a 3 prong connector, make sure that is not upside down.
Also the switch on the dash must be grounded. It gets the "Ground" thru the bracket that the switch is fixed to. You can run a wire (from one of the small nuts that hold the switch to the bracket) to a good ground. PG.