1941 Packard electric wipers won't turn off.

[Bob Stein]

I took my 1941 Packard 110 DeLuxe sedan out for a Father's Day activity today, and it started raining on the way home.  I turned on the wipers, which work great in both speeds. However, when the rain stopped I tried to turn them off with the knob and they kept going.  When I returned home, I turned off the car and turned the ignition back on.  The wipers came on.  I tried pushing the arms down with the ignition off and they still started up again as soon as they got power.  I removed the wiper arms completely, and the motor still comes on with the ignition.  I am guessing there is a park switch that is not working - anyone know if that is just a matter of cleaning points, or would I be better off trying to bypass the park feature?

[edinmass]

The ground is bad........check it with a jumper from the body of the wiper motor to the battery. That’s the easy test. If it still doesn’t stop, your park mechanism isn’t working correctly. Usually 80 percent of the time, adding a jumper to ground will solve your problems. If the jumped ground does work, remove the motor and clean all the ground contact areas. Good luck.

[Bob Stein]

Thanks for the suggestion - I did try jumping from the wiper motor body to ground, but the wipers did not stop.  I disconnected the power wire as a temporary measure, and also noted the left wiper arm was incorrect, and was able to locate a NOS one on eBay. The car came with a spare wiper motor setup, so I can check that one out.