Rear Wiper stopped working

The rear wiper on my 2001 stopped working. It first started not working every once and a while and then just stopped. It is now frozen half way on the window.

How should I go about fixing this? How do I test the motor, switch, relay, to find the problem?

Thanks in advance.

Mark.

I would remove the panel to get to the motor, check the fuse first, remove the connector at the motor, turn on the switch and check for voltage at the Red or DB/O or White wires.
My 97 Windstar has a built in non-servicable Park module, yours may be similar. If you have voltage at the connector, you will need a motor.