Combination Switch: Description and Operation

Fig.14 Multi-Function Switch:

MULTI-FUNCTION SWITCH
The multi-function switch is secured with screws to the multi-function switch mounting housing on the left side of the steering column..The switch, its mounting provisions, and its electrical connections are all concealed beneath the steering column shrouds.

A single connector connects the switch to the vehicle electrical system.

The multi-function switch supports the following functions and features:
* Continuous Wipe Modes
* Hazard Warning Control
* Headlamp Beam Selection
* Headlamp Optical Horn
* Intermittent Wipe Mode
* Turn Signal Control
* Washer Mode

The multi-function switch cannot be adjusted or repaired. If any function of the switch is faulty, or if the switch is damaged, the entire switch unit must be replaced.

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 is grounded to the chassis near the left instrument panel end bracket. When the ignition switch is in the Accessory or ON positions, battery current is provided through a fused ignition switch output (run-acc) circuit.

Following are descriptions of how the multi-function switch operates to control the many functions and features it provides:
* Continuous Wipe Modes - When the control knob of the multi-function switch is rotated to the High or Low positions, 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 switch connects the output of the wiper motor park switch to the low speed brush of the wiper motor.
* Hazard Warning Control - The hazard warning push button is pushed down to activate the hazard warning system, and pushed down again to turn the system OFF. The multi-function switch hazard warning circuitry provides a signal to the hazard warning sense of the combination flasher to activate or deactivate the flasher output to the hazard warning lamps.
* Headlamp Beam Selection - The multi-function switch control stalk 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 headlamp beam selection switch directs a ground signal output from the headlamp switch to the appropriate low beam or high beam sense of the Central Timer Module (CTM). The CTM then controls a hard wired output to activate the selected headlamp beams.
* Headlamp Optical Horn - The left multi-function switch 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 internal circuitry of the headlamp beam selection switch provides a momentary ground path to the CTM high beam sense.
* Intermittent Wipe Mode - When the multi-function switch control knob is rotated to the Delay position, the switch provides a battery current signal to the intermittent wipe module, or to the Central Timer Module (CTM). If the Delay mode is selected, the control knob can then be rotated to multiple minor detent positions, which actuates a variable resistor within the switch and provides a hard wired output to the intermittent wipe module or the CTM that signals the desired delay interval for the intermittent wiper feature.
* Turn Signal Control - The multi-function switch control stalk actuates the turn signal switch.The multi-function switch turn signal circuitry provides a signal to the right or left turn signal sense of the combination flasher to activate or deactivate the flasher output 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 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 clockspring 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.
* Washer Mode - Pushing the control knob on the end of the multi-function switch control stalk towards the steering column provides a battery current output through the momentary single pole, single throw washer switch circuitry to operate the washer pump/motor, and to provide a washer signal input to the intermittent wipe module, or to the CTM, as the vehicle is equipped.