Turn Signal Switch: Description and Operation

Multi-Function Switch:

LEFT MULTI-FUNCTION SWITCH
The left multi-function switch is mounted on the left side of the steering column. The only visible parts of the left multi-function switch are the control stalk that extends from the left right side of the steering column just below the steering wheel, and the hazard warning switch button that protrudes from the top of the steering column just below the steering wheel. The left multi-function switch control stalk and the hazard warning switch button both have International Control and Display Symbol icons on them, which identify their functions. The control stalk has icons for High Beam and Turn Warning, while the hazard warning switch button has an icon for Hazard Warning. The remainder of the left multi-function switch is concealed beneath the steering column shrouds. The left multi-function switch alone has a turn signal cancel actuator that extends from the inboard surface of the switch housing, toward the center of the steering column.

The switch housing and its controls are constructed of molded black plastic. Two connector receptacles, one with four terminal pins for the headlamp beam select functions and one with eleven terminal pins for the turn signal and hazard warning functions, are located on the back of the switch housing and connect the switch to the vehicle electrical system through two take outs and connectors of the instrument panel wire harness. The switch is secured to the upper steering column housing by a single screw. The left multi-function switch contains switches and circuitry to support the following functions:
- Turn Signal Control - The internal circuitry and hardware of the left multi-function switch provide detent switching with automatic cancellation for both the left and right turn signal lamps.
- Hazard Warning Control - The internal circuitry and hardware of the left multi-function switch provide detent switching for activation and deactivation of the hazard warning lamps.
- Headlamp Beam Selection - The internal circuitry and hardware of the left multi-function switch provide detent switching for selection of the headlamp high or low beams.
- Headlamp Optical Horn - The internal circuitry and hardware of the left multi-function switch includes momentary switching of the headlamp high beam circuits to provide an optical horn feature (sometimes referred to as flash-to-pass), which allows the vehicle operator to momentarily flash the headlamp high beams as an optical signalling device.

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.

When the left multi-function switch control stalk is moved in the upward direction, the right turn signal switch circuitry is activated; and, when the control stalk is moved in the downward direction, the left turn signal switch circuitry is activated. 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 rotates with the steering wheel and the cam lobes contact the cancel actuator when it is extended from the left multi-function switch. The cancel actuator latches against the cancel cam rotation in the direction opposite that of the turn signal direction that 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 when the steering wheel returns to center by rotating to the right, which will cancel the turn signal event and release the control stalk from the detent so it returns to the neutral OFF position.

When the headlamp switch is in the ON position and the left multi-function switch control stalk is pushed toward the instrument panel to a detent position, the headlamp beam select circuitry actuates the headlamp high beams. When the control stalk is pulled toward the steering wheel to a detent position with the headlamp switch in the ON position, the circuitry actuates the headlamp low beams. If the headlamp switch is in the OFF position and the left multi-function switch control stalk is pulled toward the steering wheel to a momentary position, the headlamp high beams will be selected until the control stalk is released. The hazard warning switch is controlled by the hazard warning switch button. Sliding the hazard switch button to the left detent position will cause the switch circuitry to activate the hazard warning lamps, and sliding the button to the right detent position will deactivate the hazard warning lamps.

The turn signal circuitry operates on battery current receive through a fused ignition switch output (run) circuit so that it will only operate when the ignition switch is in the ON position. The hazard warning and headlamp beam select circuitry operates on battery current received through a fused B(+) circuit so that it will remain operational, regardless of the ignition switch position. The turn signal and hazard warning circuitry of the left multi-function switch provides a select signal input to the combination flasher, then directs the combination flasher output to the proper lamp circuits. The headlamp beam select circuitry of the left multi-function switch directs the outputs of the headlamp switch through fuses in the Junction Block (JB) to the proper headlamp high or low beam circuits. Refer to the owner's manual in the vehicle glove box for more information on the features, use and operation of the left multi-function switch.