Left Multi-Function Switch

Fig.18 Multi-Function Switches:

LEFT MULTI-FUNCTION SWITCH
The left multi-function switch is secured to the upper steering column housing, below the steering wheel.. The hazard warning switch push button is located on the top of the multi-function switch housing.

A connector containing eighteen terminal pins is located on the back of the switch housing and connects the switch to the vehicle electrical system. A second connector on the back of the switch housing accepts the combination flasher. The right and left multi-function switches are mounted together by two screws, and the combined multi-function switch is secured to the upper steering column housing.

The left multi-function switch is the primary control for the interior and exterior lighting systems of the vehicle. The left multi-function switch supports the following functions:
- Hazard Warning Control
- Exterior Lighting Control
- Headlamp Beam Selection
- Headlamp Optical Horn
- Interior Lighting Control
- Turn Signal Control

The left 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 combination flasher and the right multi-function switch are available for separate service replacement.

The left multi-function switch uses a combination of resistor multiplexed and conventionally switched outputs to control the many functions and features it provides. The switch is grounded to the left cowl side inner panel, beneath the instrument panel. The switch receives battery current from a fuse in the Power Distribution Center (PDC), a fused B(+) circuit and, when the ignition switch is in the Accessory or ON positions, from a fuse in the fuse block through a fused ignition switch output (run-acc) circuit.

Following are descriptions of the how the left multi-function switch operates to control the many functions and features it provides:

Front/Rear Fog Lamps - The control knob on the end of the left multi-function switch control stalk is pulled outward to activate the optional fog lamps. The control knob is keyed so that it cannot be pulled outward unless the knob is first rotated to turn ON the exterior lighting. The internal circuitry of the left multi-function switch then provides battery current through a fused fog lamp relay output circuit and the fog lamp relay to the fog lamps and to the instrument cluster for control of the fog lamp indicator.

Hazard Warning System - The hazard warning push button is pushed down to unlatch the switch and activate the hazard warning system, and pushed down again to latch the switch and turn the system OFF. When the hazard warning switch is latched, 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, the push button will be in a raised position. The left multi- function switch hazard warning 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.

Headlamps - The control knob on the end of the left multi-function switch control stalk is rotated forward to its second detent from the OFF position to activate the headlamps. The internal circuitry of the left multi-function switch then provides battery current through the integral beam select switch and the headlamp low beam or high beam circuits to the appropriate headlamp filaments and to the instrument cluster for control of the high beam indicator.

Headlamp Beam Selection - The left multi- function switch control stalk is pulled towards the steering wheel past a detent, then released to actuate the integral beam select switch circuitry Each time the control stalk is actuated in this manner, the opposite headlamp mode from what is currently selected will be activated.

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 beam select switch circuitry directs battery current through the headlamp high beam circuit of the left multi-function switch to the headlamp high beams and to the instrument cluster for control of the high beam indicator.

Interior Lamps Control - A control ring on the left multi-function switch control stalk is rotated to a full forward detent to illuminate all interior courtesy lamps. The instrument cluster circuitry monitors the hard wired variable resistor output of the left multi- function switch through the panel lamps dimmer signal circuit then, based upon that input, provides a ground path to activate all interior courtesy lamps through a courtesy lamp feed circuit output.

Panel Lamps Dimming - A control ring on the left multi-function switch control stalk is rotated to one of six intermediate detent positions to select the desired illumination intensity of all adjustable instrument panel and instrument cluster lighting. The control ring is rotated forward to brighten, or rearward to dim the lighting. The instrument cluster monitors the hard wired variable resistor output of the left multi-function switch through the panel lamps dimmer signal circuit then, based upon that input, provides a pulse width modulated output, to control the instrument cluster lighting levels. The instrument cluster also controls the lighting levels of the other adjustable instrument panel lighting based upon this panel lamps dimmer signal through a panel lamps driver circuit output.

Parade Mode - A control ring on the left multi- function switch control stalk is rotated to an intermediate detent that is one detent rearward from the full forward detent to illuminate the Vacuum Fluorescent Display (VFD) in the instrument cluster and the radio at full intensity. The instrument cluster monitors the hard wired variable resistor output of the left multi-function switch through the panel lamps dimmer signal circuit then, based upon that input, adjusts the instrument cluster VFD to its full intensity and provides a battery current signal to the radio on a park lamp relay output circuit that signals the radio to light its VFD to full intensity.

Park Lamps - The control knob on the end of the left multi-function switch control stalk is rotated forward to its first detent to activate the parking lamps. The left multi-function switch then provides battery voltage to the parking lamps and to the instrument cluster as a request for cluster illumination and panel lamps output.

Turn Signal Control - The left multi-function switch control stalk actuates the turn signal switch.The multi-function switch turn signal circuitry simultaneously provides a signal to the turn signal sense circuit of the combination flasher to activate the flasher output. 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 clockspring, 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. 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 turn indicators in the instrument cluster flashes in unison with the turn signal lamps, indicating to the driver that the system is operating.