Wipers work in all modes, but won't shut off. I was told there should be a shut off in the wiper motor that's not working. Would I be able to splice in a shut off switch, where is the best place?

 

You could, but it would be very aggravating to use. You would have to stare at the wipers, and then hit the switch at the right time to make them stop at the bottom.

There is a hot wire going directly to the motor under the hood. There is also another hot wire coming from the dash switch. And like someone told you, there is a cam switch in the motor.

The motor is sitting there with that key on hot wire ready to go any time the key is in run. But it can't move because that power runs through the cam switch.

The power from the dash switch bypasses the cam switch and makes the motor start running. When you turn the dash switch off, if the wipers are not in their home position, the power from the underhood hot wire will continue to power the wipers till they hit home, and that's when the cam switch opens and stops them.

The only way to rig it up is to put a switch in the hot wire that goes to the motor under the hood. I will warn you, there are several instances when the cam switch will not work. If you are running the wiper motor with no blades rubbing the windshield, the motor will not stop. There is no drag on the motor, so it will "coast through" the cam switch dead spot and keep going. Also if you are messing around with a 6v motor on 12v, the same thing can happen, it can coast through and hesitate, but won't stop.