Windshield Washer Pump - Operation

OPERATION

The 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 headlamp and dash wire harness. The motor is grounded at all times through another take out of the headlamp and dash wire harness with a single eyelet terminal connector that is secured by a screw to the body sheet metal in the engine compartment.

The Body Control Module (BCM) (also known as the Common Body Controller/CBC) controls the washer pump/motor control circuit through a high side driver based upon electronic washer request messages received over the Controller Area Network (CAN) data bus from the Steering Control Module (SCM). The SCM monitors hard wired analog and multiplex inputs from the washer switch circuitry contained within the multi-function switch to determine the proper electronic messages to send.

Washer fluid is drawn through the pump inlet nipple from the washer reservoir to the inlet port of the washer pump housing. A filter screen integral to the pump inlet port prevents most debris from entering the pump housing. 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 circuits connected to the unit 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 electronic controls or communication between other modules and devices that provide many features of the wiper and washer system. The most reliable, efficient, and accurate means to diagnose the washer pump/motor unit or the electronic controls and communication related to washer pump/motor unit operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.