I had a module fitted to my 69 when I got it. I should rewire it again.
It interrupts the motor for a period when it detects the wipers are parked. Quite innovative in 1968!
The wiper motor has a 12 volt feed to run the motor as you would expect. When you stop the wipers, the wipers continue to drive until a position is reached when the motor is interrupted. The module uses this interrupter when the wipers are in normal use to detect the wipers are parked, and then waits a little bit until it times out, and allows them to go again. Its variable via the pot. I just didn't watch the wiring when I yanked it out, and would need to work it out again.
And a really good movie too about the guy who invented it and had it robbed from him by GM in the late 60s : http://www.imdb.com/title/tt1054588/
