Hazard Warning Lamps: Description and Operation

INTRODUCTION
Following are general descriptions of the major components in the turn signal and hazard warning systems.

SYSTEM OPERATION
Turn Signal System
With the ignition switch in the On or Accessory position, and the multi-function switch control lever moved up (right turn) or down (left turn), the turn signal system is activated. The switch has a detent position in each direction that provides turn signals with automatic cancellation, and an intermediate momentary position that provides turn signals only until the multi-function switch lever is released.

When the turn signal switch is in a detent position, it is turned off by one of two cancelling cam lobes molded into the hub of the clockspring mechanism. When turning the steering wheel causes one of the cam lobes to contact a cancel actuator in the multi-function switch, the turn signal switch automatically returns to the off position.

When the turn signal system is activated, the selected (right or left) turn signal indicator lamp, front park/turn signal lamp, and rear tail/stop/turn signal lamp bulbs will flash.

Hazard Warning System
The hazard warning system is activated by a switch button in the multi-function switch. The button is located on the top of the steering column in between the steering wheel and the instrument panel. The hazard warning switch button is identified with a double triangle.

The hazard warning system is connected to an unswitched battery feed so that the system remains functional, regardless of the ignition switch position. Push the switch button in to activate the hazard warning system, and push in on the button again to turn the system off.

When the hazard warning system is activated, the right and left turn signal indicators, front park/turn signal lamps, and rear tail/stop/turn signal lamps will flash.

Turn Signal Flasher
The turn signal flasher contains one fixed contact point, and one contact point attached to a flexible bimetal arm. The contact points are normally closed. When a turn signal is activated, current flows through the flasher. As the current flows through the bimetal arm, it heats and flexes to pull the contact points open, stopping current flow. As the bimetal arm cools, it straightens until the contact points close, then the cycle repeats.

The standard turn signal flasher is designed to handle the current flow requirements of the factory-installed lighting. If supplemental lighting is added to the turn signal circuits, such as when towing a trailer with lights, the current flow through the flasher increases. This causes the flash rate to increase. It is recommended that the standard flasher be replaced with a heavy-duty (hazard warning) flasher when supplemental lighting is added.

However, when a turn signal bulb fails with a standard flasher, the remaining bulbs in that circuit will light, but not flash. This will give the driver an indication to check the turn signal bulbs. Because a heavy-duty flasher has different internal circuitry, a failed bulb will not prevent the remaining bulbs in the circuit from flashing. Therefore, it is recommended that an occasional visual inspection of exterior turn signal lamp operation be performed, when a heavy-duty flasher has been installed in the place of the standard flasher.

Hazard Warning Flasher
The hazard warning flasher contains two normally open contact points mounted to two movable arms. A bimetal strip is attached between the two arms. When the hazard warning switch is activated, current flows through the flasher. As the current flows through the bimetal strip it heats and pulls the movable arms together until the contact points close, allowing current flow to the lamps. As the bimetal strip cools, the contact points are pushed open and the cycle repeats.

Multi-Function Switch:

Turn Signal Switch And Hazard Warning Switch
The turn signal and hazard warning switches are integral to the multi-function switch assembly. The multi-function switch assembly is mounted to the left side of the steering column. This switch contains circuitry for the following functions:
- Turn signals
- Hazard warning
- Headlamp beam selection
- Headlamp optical horn
- Windshield wipers
- Windshield washers.

The information contained addresses only the multi-function switch functions for the turn signal and hazard warning circuits. However, the multi-function switch cannot be repaired. If any function of the switch is faulty, or if the switch is damaged, the entire switch assembly must be replaced.

Turn Signal Indicator Lamp
The turn signal indicator lamps are located in the instrument cluster. They flash with the exterior turn signal lamps to give the driver a visual indication that a turn signal or the hazard warning system is operating. For diagnosis and service of these lamps, refer to Lighting and Horns/Turn Signals.

Turn Signal Lamp
The exterior lamps in the turn signal and hazard warning circuits include the front park/turn signal,and the rear tail/stop/turn signal. For diagnosis and service of these lamps, refer to Lighting and Horns.