Headlamp Switch: Description and Operation

WARNING: VEHICLES ARE EQUIPPED WITH AN AIRBAG, REFER TO AIRBAGS AND SEAT BELTS/AIRBAGS FOR STEERING WHEEL OR COLUMN SERVICE PROCEDURES.

The multi-function switch contains:
- Turn signals
- Hazard warning
- Headlamps
- Headlamp beam select
- Parking lamps
- Panel dimmer
- Fog Lamp
- Headlamp optical horn
- Windshield wiper
- Pulse wipe
- Mist wipe
- Windshield washer switches.

The multi-function switch is mounted center of the steering column. There are two levers, one on each side of the steering column.

The left side controls the signaling and lighting. The right side controls the windshield wiper and washer system.

When the driver wishes to signal his intentions to change direction of travel, he moves the left lever upward to cause the right signals to flash and downward to cause the left signals to flash. After completion of a turn the system is deactivated automatically. As the steering wheel returns to the straight ahead position the turn signals are canceled. A canceling cam is molded to the clockspring mechanism which comes in contact with the cancel actuator on the multi-function switch. The canceling cam lobe pushes on the cancel actuator and returns the switch to the off position.

If only momentary signaling such as indication of a lane change is desired, the switch is actuated to a left or right intermediate detent position. In this position the signal lamps flash as described above, but the switch returns to the OFF position as soon as the lever is released.

When the system is activated, one of two indicator lamps mounted in the instrument cluster flashes in unison with the turn signal lamps, indicating to the driver that the system is operating.

To use the washers pull lever toward the driver. The mist is a single wipe operation by pushing lever down and releasing the lever. Intermittent wiper operation is controlled by the Body Control Module (BCM). The lever has a selection of delay intervals and by turning the lever the wiper will cycle every half second to 36 seconds depending ON the vehicle's speed. The wiper has two cycle two speeds.

The windshield wipers will only operate when the ignition switch is in the ACCESSORY or IGNITION RUN position. Fuse 15, located in the Junction Block, fuses 8 and 14 in the Power Distribution Center (PDC) block, protects the wiper/washer system circuitry. The wiper motor also has an internal non-serviceable circuit breaker to provide protection against motor stall conditions.

The wiper and washer motors have magnetic fields created by internal permanent magnet. Electric power applied to the motor armature, located in the magnetic field, causes the motor to turn.

The wiper system internal operation uses the low speed motor circuit in combination with intermittent wipe relay. The washer pump motor has one internal circuit and therefore operates at one speed.

The wiper and washer system switch located on the steering column selects the mode of operation of the motors. The switch provides input to the BCM, which in turn operates the two relays. The intermittent wipe relay turns the wiper ON and OFF. The other changes the HIGH/LOW speeds. The switch also provides power to the washer pump motor.

The intermittent wiper system, in addition to low and high speed, has a delay mode. The delay mode has a range of 1/2 to 18 seconds when the vehicle speed is over 10 mph. The wiper delay times will automatically double to a range of 1 to 36 seconds when the vehicle speed is less than 10 mph. The delay is controlled by a variable resistor in the wiper switch and BCM.

The wiper motor and washer motor are designed to reduce radio frequency interference and provide electro-magnetic compatibility (RFI/EMC) in the vehicle environment. This is done with suppression circuits designed into the motors.

The wiper system completes the wipe cycle when the switch is turned OFF. The blades park in the lowest portion of the wipe pattern.

When using a scan tool (DRB) refer to the Body Diagnostic for the procedures.