Principles of Operation

PRINCIPLES OF OPERATION

On automatic headlamp equipped vehicles, the smart junction box (SJB) receives a signal from the front wiper motor when it is activated. After the wipers have been on for more than 10 seconds, the SJB will illuminate the exterior lamps.

High Speed Windshield Wipers
High speed is activated when the windshield wiper/washer switch supplies a specific ground input to the windshield wiper motor module. The module then grounds the internal park/run relay and the internal HI/LO speed relay. Voltage is then sent to the high speed side of the wiper motor, which activates the high-speed mode. High speed mode is exited by selecting a different state on the 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 Hall-effect sensor senses the motor magnet. The output to the run/park relay deactivates the relay and disconnects the voltage to the motor.

Low Speed Windshield Wipers
Low speed is activated when the windshield wiper/washer switch supplies ground inputs to the windshield wiper motor module. The module then supplies ground for the run/park relay, which activates the relay, sending voltage to the low speed side of the motor, activating the low speed mode. Low speed mode is exited by selecting a different state on the 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 Hall-effect sensor senses the motor magnet. The output to the run/park relay deactivates the relay and disconnects the voltage to the motor.

Intermittent Speed Windshield Wipers
The intermittent wiper speed is activated with grounds controlled by the multi-function switch inputs to the windshield wiper motor module. The windshield wiper motor module then activates the windshield wiper run/park relay coil and switches voltage through the windshield wiper high/low relay. The high/low relay remains deactivated supplying the voltage through the windshield wiper motor low speed input and activates the windshield wiper motor. When the windshield wiper motor module receives the grounded input, the motor continues to operate until the Hall-effect sensor senses magnetism, which turns off the run/park sensor output to the windshield wiper run/park software, deactivating the relay and disconnecting voltage to the wiper motor. The windshield wipers remain parked until the windshield wiper motor module completes a time-out and then repeats the intermittent windshield wiper cycle.

Speed Dependent Windshield Wipers
The windshield wiper motor module responds to the windshield wiper control commands by interpreting inputs from the powertrain control module (PCM) system. The speed-dependent wipers will compensate for the extra moisture that accumulates on the windshield at higher speeds, except when the multi-function switch is in the INT 1 position. At higher speeds, the speed dependent feature shortens the delay between wipes when using the variable interval wipers. Delays will automatically adjust at speeds between 16 and 105 km/h (10 and 65 mph).

Intermittent Rear Window Wiper System
The rear window wiper intermittent speed is activated when the rear window wiper motor module receives ground controlled by the multi-function switch inputs to the rear window wiper motor module. The rear window wiper motor module then activates the rear window wiper relay (internal) by momentarily grounding the relay coil. This activates the rear window wiper motor by providing voltage from the battery junction box (BJB). Once the rear window wiper motor is activated, it's internal run/park switch connects voltage to the motor, keeping it operating. When the rear window wiper motor returns to the park position, the run/park switch disconnects voltage internally from the wiper motor input, reconnecting it to the rear window wiper motor module output. The rear window wiper remains parked until the rear window wiper motor module completes a time-out and then repeats the cycle.

Washer System
The windshield washer and the rear window washer are activated by the internal wiper motor modules when they receive a ground from the multi-function switch between the washer inputs. Depending on the correct ground, the internal wiper motor modules activate either the windshield washer or the rear window washer relays (internal) by grounding the respective relay coil. When either relay is activated, it connects voltage to the washer pump while the deactivated relay provides ground to the washer pump. In this manner, voltage polarity is reversible to achieve directional change of the washer pump and washer fluid.

Software Safe Mode
The windshield 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 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.