Principles of Operation (How Does it Work?)

The windshield wiper motor is a two speed motor that uses the motor case as the path to ground. The motor contains a park switch. This park switch switches between a path to ground when the motor is in the park position and a 12 V potential when the motor is turning.

When the multifunction switch is in the low and high speed position, the windshield wiper motor receives voltage from fuse 20, directly through the multifunction switch. When the multifunction switch is in the intermittent position, single wipe position, or when the front windshield wiper is reaching the park position, the windshield wiper motor receives voltage by the CTM controlling the windshield wiper relay, allowing voltage to pass through the multifunction switch to the windshield wiper motor.

When the multifunction switch is in the intermittent position the windshield wiper motor is controlled by the CTM. The CTM determines the position of the variable intermittent wipe position of the multifunction switch to determine the amount of time between wipes of the windshield wiper. When appropriate, the CTM then grounds the coil side of the windshield wiper relay, to actuate the windshield wiper motor.

The washer pump is used for both windshield washers and rear window washer. With the multifunction switch in wipe/wash position the ground path for the washer pump is through the CTM and voltage through the multifunction switch. With the multifunction switch in the windshield wiper position both ground and voltage are supplied by the multifunction switch. With the multifunction switch in the rear washer position voltage and ground are applied to the washer pump with opposite polarity. The washer pump will turn in the opposite direction.

The rear window wiper motor is a single speed motor that uses its case for a ground. The motor only receives voltage from the multifunction switch.