Turn Signal Indicator: Operation

The turn signal indicators give an indication to the vehicle operator that the turn signal (left or right indicator flashing) or hazard warning (both left and right indicators flashing) have been selected and are operating. These indicators are controlled by transistors on the instrument cluster electronic circuit board based upon the cluster programming and a hard wired input received by the cluster from the turn signal relay through the turn signal and hazard warning switch circuitry of the multi-function switch on the left and right turn signal circuits. Each turn signal indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will allow this indicator to operate whenever the instrument cluster receives a battery current input on the fused B(+) circuit. Therefore, each LED can be illuminated regardless of the ignition switch position. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn on the turn signal indicators for the following reasons:

• Turn Signal Input  - Each time the cluster detects a turn signal input from the turn signal relay through the closed turn signal switch circuitry of the multi-function switch on the hard wired left or right turn signal circuit, the requested turn signal lamps and turn signal indicator will be flashed on and off, and a contactless relay soldered onto the cluster electronic circuit board will produce a clicking sound to emulate a conventional turn signal flasher. The turn signals and the turn signal indicators continue to flash on and off until the turn signal switch circuitry of the multi-function switch is opened, or until the ignition switch is turned to the Off position, whichever occurs first.
• Hazard Warning Input  - Each time the cluster detects a hazard warning input from the turn signal relay through the closed hazard warning switch circuitry of the multi-function switch on the hard wired left and right turn signal circuits, all of the turn signal lamps and both turn signal indicators will be flashed on and off, and a contactless relay soldered onto the cluster electronic circuit board will produce a clicking sound to emulate a conventional hazard warning flasher. The turn signals and the turn signal indicators continue to flash on and off until the hazard warning switch circuitry of the multi-function switch is opened.

An electronic wipers, turn signals and engine start control module located within the fuse block beneath the steering column monitors the turn signal circuits and controls the flash rate of the turn signal relay. The instrument cluster continually monitors the right and left turn signal circuits to determine the proper turn signal and hazard warning indicator operation, then flashes the proper turn signal indicators and the contactless relay on and off accordingly. The multi-function switch, the turn signal relay and the left and right turn signal circuits to the instrument cluster can be diagnosed using conventional diagnostic tools and methods. For proper diagnosis of the wipers, turn signals and engine start control module within the fuse block or the instrument cluster circuitry that controls the turn signal indicators and the contactless relay, a diagnostic scan tool is required. Refer to BODY DIAGNOSTIC PROCEDURES .