Principles of Operation

Wipers and Washers

Principles of Operation

NOTE: The Smart Junction Box (SJB) may also be identified as the Generic Electronic Module (GEM).

When the ignition switch is in the RUN or ACCESSORY position, voltage is supplied to the wiper relay coil at the Battery Junction Box (BJB) from SJB (Smart Junction Box) fuse 45. The wiper relay coil is grounded at all times. Voltage is supplied to the wiper relay switch from BJB (Battery Junction Box) fuse 4. When the wiper relay is activated, voltage is supplied to the wiper motor.

Wipers and Washers

The windshield wiper system consists of a wiper relay and an integrated wiper motor and module assembly, which contains internal washer, run/park and high/low speed relays. The windshield wiper motor and module assembly also contains a Hall-effect sensor that is used to determine the parked position of the wiper motor during a cycle. The integrated windshield wiper motor and module assembly has 5 different operating modes: OFF, LOW speed, HIGH speed, INTERMITTENT and SOFTWARE SAFE mode.

High-Speed Wipers

When the multifunction switch is set to the HIGH speed position, it supplies ground to the internal high/low speed relay coil and the internal run/park relay coil, which causes the windshield wiper motor to operate at high speed. During high-speed operation only, both the internal high/low-speed relay coil ground and the internal run/park relay coil ground are controlled directly by the multifunction switch. This differs from LOW speed or intermittent operation when the internal run/park relay coil is controlled by the microprocessor. When the switch is placed in the OFF position, the motor continues to operate until the motor returns to the PARK position and the internal Hall-effect sensor senses the motor magnet. The output to the internal run/park relay deactivates the relay and disconnects the voltage to the motor.

Low-Speed Wipers

When the multifunction switch is set to the LOW-speed position, it supplies ground to the internal wiper motor module low-speed inputs and the wiper motor operates at low speed. During low-speed operation, the internal run/park relay is activated by the microprocessor and supplies 12 volts to the low-speed brush of the wiper motor. The internal run/park relay coil ground is controlled by the internal wiper motor module based on inputs received from the multifunction switch. When the switch is placed in the OFF position, the motor continues to operate until the motor returns to the PARK position and the internal Hall-effect sensor senses the motor magnet. The output to the internal run/park relay deactivates the relay and disconnects the voltage to the motor.

Intermittent Wipers

When the multifunction switch is set to the intermittent position(s), it supplies ground to the wiper motor module inputs and the wiper motor operates in intermittent mode. During intermittent operation, the wiper motor activates the internal run/park relay coil which sends voltage through the internal high/low relay. The internal high/low relay remains deactivated, supplying the voltage to the low-speed brush of the wiper motor. The wiper motor continues to operate until the internal Hall-effect sensor senses the magnet (PARK position) and deactivates the internal run/park relay, which disconnects voltage from the wiper motor. The windshield wipers remain parked until the wiper motor module completes a time-out and then repeats the intermittent wiper cycle.

Wiper Activated Headlamps

The SJB (Smart Junction Box) sends a voltage signal to the wiper motor module in order to monitor the status of the wipers. When the headlamps control switch is in the AUTOLAMP position and the wipers are on, the SJB (Smart Junction Box) activates the headlamps within 10 seconds. When the SJB (Smart Junction Box) detects that the wipers have been turned off, the SJB (Smart Junction Box) turns off the headlamps after 30 seconds.

Rain Sensitive Wipers (if equipped)

The rain sensitive feature replaces the intermittent wiper feature. When the rain sensitive wiper system is active, the rain sensor sends data to the wiper motor. The wipers activate based on the amount of moisture detected on the windshield and the setting on the multifunction switch.

The rain sensor optically senses water on the windshield. An infrared beam lights a section of the windshield. The intensity of the reflected beam is measured and compared to the intensity of the transmitted beam. If there is water on the surface of the windshield, the beam distorts, reducing the intensity of the beam. If the beam is not reflected completely, it is interpreted as rain on the windshield and the windshield wipers are activated.

If a fault is detected with the rain sensor input by the windshield wiper motor, the wiper motor switches to a default intermittent mode. The timing of the wipers correspond to a standard intermittent setting based on the selection on the multifunction switch.

A gel-type lens is used as the interface between the rain sensor and the windshield. If the lens is missing or damaged, the rain sensing wipers may be inoperative. If the rain sensitive wipers are inoperative and do not default to the intermittent mode, inspect the rain sensor and confirm that the gel-type lens over the rain sensor is undamaged.

Washer

When the wash function is selected on the multifunction switch, the wiper motor module activates the integral washer relay which sends voltage to the washer pump to direct fluid to the windshield.

Software Safe Mode

The wiper motor defaults to software safe mode when the run/park sensor does not sense the Hall-effect magnet inside the wiper motor. This can be caused by an obstruction of the windshield wipers, a binding linkage or loss of the Hall-effect sensor signal. The motor continues to operate in a high/low-speed condition, and when turned off, the wipers immediately park on the windshield. If necessary, the wipers can be turned on and off until they return to the PARK position.

Wiper Circuit Function Table