Need a wiring diagram for the windshield wiper motor for a 1991 Volkswagen Jetta

Three different faults. Get a competent person to carry out a diagnostic test to verify the faults.
Probably a faulty door lock unit, faulty horn and rear wiper motor fail due to water ingress.

Washer fluid is probably frozen, have you checked the fuse for the wipers? There should be an overload protection in case the blades stick

HTH

Best if you have a wiring diagram of at least the part of
the curcuit your going to work on (wiper circuit)

That applies to any electrical issue,simply can't start your
checking or testing without a road map.

If it were to guess for you,I would say the motor has failed

Even with a wiring diagram it isn't always easy to jump it
once out of the car,to test it. You won't have the internal
wiring diagram for the motor.

The switch you can turn on & use your volt meter at the
wiper motor with it disconnected,but again need to have the
diagram to probe the correct wires

Have you replaced only the motor or including the gear box (where the input shaft to the linkages is located)?

sounds like they need to be re-adjusted

YOU NEED TO TURN OFF RADIO FIRST THEN DISCONNECT NEGATIVE BATTERY CABLE. YOU NEED TO MARK POSITION OF THE WIPER ARMS ON THE WINDSHIELD YOU CAN USE WHITE OUT LIQUID PAPER TO MARK WIPER ARMS LOCATION.THEN REMOVE WIPER ARMS,REMOVE THE COWL COVER,REMOVE THE WIPER MOTOR LINKAGE MOUNTING BOLTS.REMOVE ASSEMBLY, DISCONNECT THE ELECTRICAL CONNECTOR AND UNBOLT THE MOTOR FROM THE LINKAGE.

the linkage to the wiper came apart, remove the cowling at the base of the windshield and check linkage

wiper gears may be broken, got to junk yard and buy motor and gear assembly for windshield wipers, should only take an hour to change out.

lift the plastic cover at the bottom of the wiper arm,tighten the nut that is there,the spline in the wiper arm is loose

check windshield wiper fluid level, it's probably low.