Operating Modes

WARNING: This page is about a different car, the 2015 Fiat 500. However, it is still accessible from the selected car via links, so may be relevant.

Following are paragraphs that briefly describe the operation of each of the rear wiper and washer system operating modes.

Intermittent Wipe Mode - When the right (wiper) multifunction switch control knob is moved to the Delay (or Intermittent) position, the switch provides a resistor multiplexed input to the BCM. The BCM responds by energizing a relay that directs battery current to the rear wiper motor, causing the rear wiper to cycle at a fixed intermittent speed.
When the Off position of the right multifunction switch control knob is selected, the switch provides a resistor multiplexed input to the BCM. The event that occurs depends upon the position of the wiper blade on the liftgate glass at the moment that the control knob Off position is selected.

If the wiper blade is in the down position on the liftgate glass when the Off position is selected, the park switch that is integral to the wiper motor is an open circuit, which provides a hard wired park switch sense input to the BCM. The internal BCM circuitry pulls the park switch sense input to ground when the switch is open so that the microcontroller sees a ground when the wiper blade is parked. The BCM then de-energizes the wiper motor and the wiper motor ceases to operate.

If the wiper blade is not in the down position on the liftgate glass at the moment the Off position is selected, the park switch is a closed circuit to fused ignition output voltage and the BCM continues running the wiper motor at low speed until the wiper blade is in the down position on the liftgate glass and the park switch input to the BCM is again an open circuit that the BCM circuitry pulls to ground.
Wash Mode - When the control stalk of the right (wiper) multifunction switch is pushed forward to the momentary rear WASH position, the switch provides a resistor multiplexed input to the BCM. The BCM responds by directing battery current and ground to the washer pump/motor as well as battery current to the rear wiper motor. The washer pump is de-energized as soon as the control stalk is released, but the rear wiper motor continues to operate for several continuous cycles before parking at the base of the glass or reverting to the fixed delay interval operation.
The BCM uses a hard wired output from a park switch internal to the rear wiper motor as an additional logic input to monitor the position of the rear wiper blade on the glass and to control the number of wiper sweeps following washer operation.