[Belix]

Good day all
I'm trying to track an issue with the rear wiper no longer working. I suspect the usual issue of fatigue in the wires through the rubber tailgate grommet. However, I note the wiper motor plug has four wires. I would assume an negative (the black wire shows continuity with negative), a constant 12V for auto park, and the switch 12V, but what is the last?
Does anyone knows what each is for?

 

[AUTOSPARK]

Does anyone knows what each is for?

As you rightly say :
one wire is an ignition +12V power supply for the self park switch
one is ground
and one is a +12V power supply from the rear wiper switch

The 4th wire is the output of the self park switch inside the motor. That wire is switched to ground when the motor is in the park position, and switched to +12V while the motor is in motion. A break in this wire wouldn't prevent the motor from operating. It just wouldn't park when the switch is moved to OFF.

If I helped you fix it, why not...

Your support is greatly appreciated​