Front Windshield Washer Pump - Operation

FRONT

The front washer pump/motor unit features a small Direct Current (DC) electric motor. The motor is connected to the vehicle electrical system through a single take out and two-cavity connector of the vehicle wire harness. The motor receives battery current whenever the ignition switch is in the ON position.

The motor receives ground and is energized through a low side driver within the Body Control Module (BCM) (also known as the Signal Acquisition and Actuation Module/SAM) whenever the BCM receives an electronic message requesting washer system operation from the Steering Control Module (SCM) (also known as the steering column module/MRM) over the Controller Area Network (CAN) data bus. The SCM monitors an input from the momentary front washer switch contacts within the multi-function switch on the steering column to determine when it should issue the electronic message requesting front washer system operation.

Washer fluid is gravity-fed from the washer reservoir to the inlet side of the washer pump. When the pump motor is energized, the motor spins the rotor within the washer pump. The spinning pump rotor pressurizes the washer fluid and forces it through the pump outlet nipple, the washer plumbing, and the washer nozzles onto the windshield glass.

The washer pump/motor unit and the hard wired motor control circuit from the BCM may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the front washer pump/motor unit or the electronic controls or communication between other modules and devices that provide some features of the front wiper and washer system. The most reliable, efficient, and accurate means to diagnose the front washer pump/motor unit or the electronic controls and communication related to front washer pump/motor unit operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.