RAM 1500 Truck 4WD V8-5.9L VIN Z (2002)
Windshield Washer Pump: Description and Operation
Fig. 10 Washer Pump/Motor
WASHER PUMP/MOTOR
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
connector that is secured by a nut to a ground stud located on the right front fender inner shield in the engine compartment. The washer
pump/motor receives battery current on a washer pump/motor control circuit through a high side driver within the Front Control Module (FCM)
whenever the FCM receives an electronic message from the instrument cluster over the Programmable Communications Interface (PCI) data bus
requesting washer system operation. The instrument cluster monitors a resistor multiplexed hard wired input from the momentary washer switch
contacts within the multi-function switch on the steering column to determine when it should issue the electronic message requesting washer
system operation.
The washer pump/motor unit can be diagnosed using conventional diagnostic tools and methods. However, conventional diagnostic methods may
not prove conclusive in the diagnosis of the instrument cluster, the Front Control Module (FCM), or the electronic message inputs to or outputs
from the instrument cluster and the FCM that control the operation of the washer pump/motor unit. The most reliable, efficient, and accurate
means to diagnose the washer pump/motor unit, the instrument cluster, the FCM, or the electronic message inputs and outputs related to the washer
