2003 Ford Crown Victoria windshield wipers

The insane engineers have added a computer module to the wiper motor. Did you replace just the motor or the entire assembly with that computer? The computer is the most likely suspect. The switch is the least likely because there's actually three switches built into one assembly, and all three would have to be defective for the wipers to not work in any setting.

The next most common suspect is a bad ground for the motor. They're usually mounted on a plate that is mounted on rubber bushings to isolate the vibration. To identify this, turn the ignition switch and wiper switch on, then use a grounded test light to check for voltage on the metal case of the wiper motor. If you find voltage there, attach a ground wire between the motor and the car's body.

Dandy. Sometimes the wires break from repeated flexing of the tilt steering column. There's no good way to splice wires where they flex. Instead, run new sections of wire to where they can be spliced where they won't flex. Push the strands of wire into each other to create a smooth splice. Don't twist the wire ends together. Solder the splices, then seal them with heat-shrink tubing. When you do this outside the passenger compartment, use heat-shrink tubing with hot-melt glue inside to seal out moisture. You may need to splice in longer pieces of wire than you cut out to prevent them from being stretched or flexed in just one small area.

By grounding a wire, you may be tricking the computer into doing something to run the motor, but to have it stop for a while suggests an auto-resetting circuit breaker is turning off. There is also a circuit that is supposed to be grounded when you turn the wipers off, but just for a second. That is to turn the motor into a generator momentarily. The wipers put a load on it that prevents the motor from coasting to a stop. If it were to coast, it would go so far as to cause the wipers to turn back on and take another swipe, then try to park again. That circuit only gets grounded briefly and only after you've turned the wipers off, or the delay mode is going into "stop" mode. If you keep that circuit grounded when the motor gets voltage to run, there will be a direct short and the circuit breaker will trip. Those are used instead of fuses in safety systems so they will attempt to start working again and not leave you in a rain storm unable to see.

Also, any wire that is supposed to be grounded will never be grounded in the steering column. It will be grounded under the dash. Any wire going up the steering column is there because it needs to go to someplace. What I'm trying to say is a wire wouldn't be running up the column if it could have been grounded somewhere else.