Thanks to
hatzie, you can download a factory wiring diagram here -->
http://67-72chevytrucks.com/vboard/s...d.php?t=545416
The 78-up wiper motors have 3 connectors:
(1) The 3-terminal connector near the lower end of the motor has a +12V feed and two switched ground connections that are wired back to the switch. The switch is on the ground side of the circuit.
(2) The 2-terminal connector up near the top is for the parking switch. That is responsible for returning the blades back to the parked position at the base of the windshield when the dash switch is turned off.
(3) The other 2-terminal connector with the larger wide blades out on the front is for the washer pump solenoid. One of those terminals is +12V feed and the other is a switched ground. Again, the wiper switch is on the ground side of this circuit.