I'm trying to wire in a park function on my '86 wiper motor. The system was originally controlled by an integrated control board in the wiper switch which is no longer present as the car was torn down for track use.

The wiper motor operates of a constant power and ground, using switched grounds on the L/W and L/ar wires and produces a 12v signal at its park location via the L/B wire. I currently have proof of concept running the low speed L/W wire to ground through a toggle and in parallel through an electromechanical relay on its normally closed configuration.

In theory the 12v signal produced by the motor should trigger the relay and break the normally closed position stopping the wipers. However as soon as the key is turned the wipers will run (unless manually placed in their park position) hit the internal switch, produce the 12v trigger and briefly cut the ground circuit causing the motor to stop running. However the momentum from the wipers drives the motor past park and closes the relay again when it loses its trigger and the wipers keep going until ignition power is cut.

Would use of a solid state relay with a lower response time be suitable to break the circuit fast enough to keep the motor in its park position or should I just accept that I'll have to get good at timing the wipers to stop them with the toggle at the bottom of the window.

Thanks in advance

 

Did you ever figure this out?

 

I did. Added in a second relay passing primary power through the normally closed circuit that receives a power signal in the park position from another wire (I'll have to check and get back about which wire) to kill open that relay disrupt the power supply. I'll be in the garage later today so if I remember I'll post up which wire I used