Driving in my '88 Auto. when the rear wiper just started wiping and wouldn't
stop. I replaced all the console switches about 6 months ago with new oem from
928 Specialist and all have been working perfectly. I can't believe the switch
has already gone bad. What else should I check?
Open the rear tool panel and find the wiper relay. With the ignition switch on, check for power on the green/black wire. If there is power on the wire, the switch may be hanging on the vinyl edge around the opening. If there is no power on the wire, and the wiper is still running, check for power on the green wire between the relay and the wiper motor. If there is power on the green wire with no power on the green/black wire, the relay is probably bad.
If there is no power on the green wire, and the wiper motor is still running, the park switch inside the wiper motor is stuck closed.