When turned off, wipers stop in middle of windshield (straight up) not in horizontal rest position; have tried nothing

Turn off the ignition with them at the rest position. It should reverse it and trick the module controlling them.

Pull off the wiper arms when the motor has turned off and the wipers at rest. Realign the arms in the position desired and do a test with a mist of water on the glass. The gear alignment is critical to the way the arm rests when in operation and when at rest.

The control board on the wiper motor has ametal "stop" that got bent.
This usually happens when the wipers are stuck ( frozen from ice?) and turned on.
This can be readjusted bu bending back to original position or replacing the control board
About $35 for part

Try to run the motor without the wiper arms tightened down and turn it off so it can cycle down to its rest state. Then install the wiper arms.

Make sure, that the car's windshield wiper wiring is correct for this motor.
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Wiper Arm & Blade Removal & Installation Front To Remove:
CAUTION
When the wipers are parked (off), the driver’s wiper arm must be above the passenger’s wiper arm.

1. Remove the clip holding the outside end of the wiper arm cover to the arm.
2. Lift the arm cap up to expose the nut.
3. Remove the wiper arm mounting nut.
4. Using a suitable two jaw puller, remove the wiper arm from the wiper pivot.

To Install:

1. Verify that the wiper motor and linkage are in the parked position.
2. Place the wiper arm in position over the wiper pivot.
3. Install the nut to hold the wiper arm to the wiper pivot. Torque nut to 26 ft. lbs. (35 Nm). CAUTION
   Make sure to tighten the wiper arm nut properly.
   
4. Push the arm cap cover down.
5. Secure the clip holding the cover to the wiper arm.

Rear To Remove:

1. Lift and hold the wiper arm away from the rear window.
2. Lift the lock securing the wiper arm to the pivot.
3. Slowly release the wiper arm so it rests against the lock.
4. Remove the wiper arm from the pivot.

To Install:

1. Install the wiper arm on the pivot.
2. Pull the arm outward and release the lock.
3. Gently release the wiper arm until it rests on the rear window.

hi you can try, removing both wiper arms then turning wipers on ( without arms connected ) then turn them off, once set as normal refit the the arms in correct position then you should be sorted...hope this helps please vote thanks

Remove the arms,and place them back on where they need to go,do not turn the wipers on,do this as they set now.If the wiper blades when turned on go off the left side of the windshield ,then you will have to remove everything again,and move the wipers down in the rest position,and align everything up to the rest position,with the wipers at rest,and the motor at rest.

check to make sure the wipers are at its right angle on the vehicle, loose the nuts and place both wipers close to the bottom of the wind screen

It sounds like the the circuit board has gone bad and does not know where the base is any more so it will stop at the middle or the windshield. Auto Zone should have a new board if it's replaceable like the GM products. Good luck and hope this helps, In the mean time you can always turn your wipers on and pull the fuse out when it's at the down position so it's not up.

The problem could be a bent parking pall bracket. This is usually caused when you wipe snow from windshield using the wipers instead of brushing off. You need to remove both wipers and the cover from the drivers side. Remove the cover over the wiper motor assembly (held by a plastic button). On the right side of the wiper mechanism is a small tab (part of the wiper bracket). This tab needs to be straight for the wiper park pall to rest against.Carefully hammer this tab straight (or you may have to replace bracket, big job) Then cycle the wiper and you will see the assembly return to park position. Re-install all parts in reverse order.
Hope this works for you.

the "horizontal park" mechanism is in the actual wiper motor assy.