Multifunction Switch - Operation

OPERATION

LIGHTING

The multi-function switch provides input for the exterior and interior lighting to the Body Control Module (BCM). The switch is grounded through the Body Control Module (BCM). When the ignition switch is in the ACCESSORY or ON positions, battery current from a fuse in the Power Distribution Center (PDC) is provided through a BCM controlled ignition switch output (RUN/ACC) circuit. The BCM controls the circuit protection and logic for the Low Beam relay, High Beam, Park Lamps and Fog Lamp circuitry. The BCM also controls the circuit protection and logic for the two RUN only feeds, RUN/ACCESSORY feed, and the Ignition Off Draw (IOD) feed.

The multi-function switch controls the following headlamp features and provides:

- Headlamp Beam Selection - The turn signal control stalk on the left side of the multi-function switch is pulled towards the steering wheel past a detent, then released to actuate the headlamp beam selection switch. Each time the control stalk is actuated in this manner, the opposite headlamp mode from what is currently selected will be activated. The internal circuitry of the headlamp beam selection switch directs the output of the headlamp switch to the BCM and the BCM will activate the selected headlamp beam.
- Headlamp Optical Horn - The turn signal control stalk is pulled towards the steering wheel to just before a detent, to momentarily activate the headlamp high beams. The high beams will remain illuminated until the control stalk is released. The input is detected by the BCM and the BCM will control the output.
- Turn Signal Control - The turn signal control stalk actuates the turn signal switch. When the control stalk is moved in the upward direction, the right turn signal circuitry is activated; and, when the control stalk is moved in the downward direction, the left turn signal circuitry is activated. The multi-function switch turn signal circuitry simultaneously provides a signal to the turn signal sense of the combination flasher to activate or deactivate the flasher output, and directs the output of the flasher to the proper turn signal lamps. The turn signal switch has a detent position in each direction that provides turn signals with automatic cancellation, and an intermediate, momentary position in each direction that provides turn signals only until the left multi-function switch control stalk is released. When the control stalk is moved to a turn signal switch detent position, the cancel actuator extends toward the center of the steering column. A turn signal cancel cam that is integral to the clock spring mechanism rotates with the steering wheel and the cam lobes contact the cancel actuator when it is extended from the multi-function switch. When the steering wheel is rotated during a turning maneuver, one of the two turn signal cancel cam lobes will contact the turn signal cancel actuator. The cancel actuator latches against the cancel cam rotation in the direction opposite that which is signaled. In other words, if the left turn signal detent is selected, the lobes of the cancel cam will ratchet past the cancel actuator when the steering wheel is rotated to the left, but will unlatch the cancel actuator as the steering wheel rotates to the right and returns to center, which will cancel the turn signal event and release the control stalk from the detent so it returns to the neutral 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.

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.

WIPERS

The multi-function switch uses conventionally switched outputs and a variable resistor to control the many functions and features it provides using hard wired circuitry. The switch uses body ground (Z1) when the ignition switch is in the Accessory or ON position, battery current from a fuse in the Power Distribution Center (PDC) is provided through a BCM controlled ignition switch output (RUN/ACC) circuit.

- Continuous Wipe Modes - When the control knob is in the OFF position, the wiper system completes the cycle and the blades park in the lowest portion of the wipe pattern When the control knob of the windshield wiper/washer control stalk on the right side of the multi-function switch is rotated to the High or Low positions, the circuitry within the switch provides a battery current output directly to the high or low speed brush of the wiper motor. When the control knob is in the OFF position, the wiper system completes the cycle and the blades park in the lowest portion of the wipe pattern.
- Intermittent Wipe Mode - When the windshield wiper/washer control switch control is rotated to the Delay position, the circuitry within the switch connects the output of the wiper motor relay to the low speed brush of the wiper motor and provides battery current.
- Washer Mode - Pulling windshield wiper/washer control towards the steering wheel provides a battery current output through the momentary single pole, single throw washer switch circuitry to operate the washer pump/motor.

HAZARD WARNING SYSTEM

The hazard warning switch is pushed down to unlatch the switch and activate (turn ON) the hazard warning system, and pushed down again to latch the switch and turn the system OFF. When the hazard warning switch is latched (hazard warning OFF), the push button will be in a lowered position on the top of the steering column shroud; and, when the hazard warning switch is unlatched (hazard warning ON), the push button will be in a raised position. The multi-function switch hazard warning circuitry simultaneously provides a signal to the hazard warning sense of the combination flasher to activate or deactivate the flasher output, and directs the output of the flasher to the hazard warning lamps. When the hazard warning system is activated, the combination flasher will cause both the right and left side turn signal indicator lamps, front park/turn signal lamps, front side marker lamps and rear turn signal lamps to flash ON and OFF. If the exterior lamps are turned OFF, the front park/turn signal lamps and the front side marker lamps will flash in unison. If the exterior lamps are turned ON, the front park/turn signal lamps and the side marker lamps will flash alternately.