'94 minivan rear wiper problems

I know this subject has been covered before as I've searched the
archives. However, I've still got some questions.

This van belongs to my father-in-law so I don't really know all the
history except that the rear wiper wouldn't shut off. Actually the
wiper arm was not moving but the motor was making a noise as if not
engaging the gearbox properly. This would happen even with the switch
off. So he disconnected the harness at the motor.

This is where I come in as he asked to me to take a look at it. I
plugged the harness connector back together and hear the noise from the
motor/gearbox; wiper blade does not move. As stated earlier, this
occurs with the key on but the wiper switch off. So I've taken the
blade off (yeah, that was fun) then removed the motor. Upon bench
testing the motor, I can hear it running with 12 volts applied but the
shaft doesn't turn. Obviously a new motor is needed. That I can do.
But here's my question:

Why did the old motor try to run even with switch off? There are two
wires in the harness that connects to the motor, a brown with pink
stripe wire and a brown with green stripe wire. The brown/pink wire
has voltage with the key on and wiper switch off. The brown/green wire
gets voltage with key on and switch on but only every eight seconds or
so. I think this is correct. Will replacing the motor correct all the
problems or could there still be a problem between the switch and
motor?
Thanks for any help.

 

12 volts is at the rear wiper when the key is on. The switch grounds when a
request for the wiper motor occurs. 2 things, either the ground wire (from
the motor to the switch) is shorted to ground or the switch is bad.
Disconnect the switch and the wiper motor should turn off.

Glenn Beasley
Chrysler Tech

 

OK, I'll check that out. Thanks Glenn.

 

Here's the answer: All wipers do that. Wipers will run with the switch off
until they park. Try it. If the arm doesn't move, it'll never park, so
that'swhy it never shut off. Simple.

There is a set of contacts in any wiper motor (on any car) that tells it
where to stop.

 

That's it then. The motor spins but the shaft that the blade fits onto
does not. Excellent. Thanks much.

 

The gears are notorious for stripping out.