windshield wiper stopping issue

MEXICOWANDERER wrote:
It's a limit switch over-ride. To test the "theory" yourself, grab a test light go to the wiper motor and stab wires or stick the probe into the connector block. Yes, chopping off the ignition switch does stop the motor.

Shut off the switch when wipers are in motion. They stop. Shut off the wiper switch then turn the key back on. The wipers park with the wiper switch turned off.

Many switch/park motors operate with a battery hot going into the motor. Then a "relay trigger" comes from the wiper switch to a genuine relay. This powers the wiper motor. Shut off the switch and the relay plays dead. Something needs to over-ride the relay that now has no power to the coil nor going through the power points. The battery voltage only powers the wiper motor until the cam opens the limit switch contacts. The relay over-rides the limit switch - when key is on and relay is operating. Yes this means 2 fused circuits. One for power, the other for the switch.

The test light will reveal all :)

We agree on how the park system works, other than I still say the "battery" power to provide the power to park comes from the ignition, not always-hot battery power. So one wiper-switched iginiton-based power source for normal operation and one ignition power source to provide park. Both can certainly share one fuse. Relays may be involved but only to reduce loads on switches.

I've had more than one wiper motor apart and fixed park issues before.

Now on some (most?, all?) later model vehicles, the computer controls the motor, using input from the switch and a low power park sensor signal (which is still in the motor). My buddy's Ram wipers sometimes just keep running a couple more cycles when turned off because the park pulse is missed by the computer.

Our Yukon runs the wipers when you wash and even does a spare wipe several seconds later but only if you're traveling at lower speeds so undoubtedly it's all computer controlled.