RAM 1500 Truck 4WD V8-5.9L VIN Z (2002)
Windshield Washer Motor: Description and Operation
Fig. 10 Washer Pump/Motor
WASHER PUMP MOTOR
The washer switch is a direct input to the instrument cluster. The instrument cluster sends a PCI bus message to the FCM informing it of a request
to wash. The washer pump motor is then powered through low side control inside the FCM.
This circuit is electronically controlled and continuously monitored for malfunctions. In addition, the FCM electronically protects the washer
pump motor from system voltages higher than 16 volts by automatically switching OFF the low side circuit. The low side circuit is connected to
pin 45 in the FCM connector.
If the FCM receives a prolonged request to wash lasting 30 seconds or more, it will treat the request as a stuck switch condition and deactivate the
washer pump motor. The FCM will not reactivate the washer pump motor until there is at least a two second break in the request to wash from the
instrument cluster.
The washer pump/motor unit is located on the outboard side of the rearward facing surface of the washer reservoir, in the right front corner of the
engine compartment. A small permanently lubricated and sealed electric motor is coupled to the rotor-type washer pump. A seal flange with a
barbed inlet nipple on the pump housing passes through a rubber grommet seal installed in a dedicated mounting hole of the washer reservoir.
When the pump is installed in the reservoir a barbed outlet nipple on the pump housing connects the unit to the washer system through a short
washer reservoir hose.
The washer pump/motor unit is retained on the reservoir by the interference fit between the barbed pump inlet nipple and the grommet seal, which
is a light press fit. The top of the washer pump is also secured to the washer reservoir by the use of a snap post on the motor housing and a snap
post receptacle molded into the reservoir that allows for mounting of the washer pump without the use of fasteners. An integral connector
receptacle on the top of the motor housing connects the unit to the vehicle electrical system through a dedicated take out and connector of the right
headlamp and dash wire harness. The washer pump/motor unit cannot be repaired. If faulty or damaged, the entire washer pump/motor unit must
be replaced.
The washer pump/motor unit features a 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 right headlamp and dash wire harness. Washer fluid is gravity-fed from the washer reservoir to the
inlet side of the washer pump. When the pump motor is energized, the rotor-type pump 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 is grounded at all times through a take out of the right headlamp and dash wire harness with a single eyelet terminal
