System Operation

Turn Signal and Hazard Lamps

System Operation

System Diagram





Network Message Chart

BCM (Body Control Module) Network Input Messages






Turn Signals

The SCCM (Steering Column Control Module) monitors the multifunction switch position. When the multifunction switch is in the left or right TURN position, the SCCM (Steering Column Control Module) sends a turn signal switch_status message over the communication network to the BCM (Body Control Module) indicating a request for the left or right turn signal.

When the BCM (Body Control Module) receives a request for a turn signal, the BCM (Body Control Module) supplies on/off voltage to the appropriate turn lamps.

The timed on/off cycle for turn lamps is determined by the BCM (Body Control Module) and is set to flash approximately 80 times per minute if both the front and rear turn signal lamps operate correctly. If an individual turn signal lamp is inoperative, the BCM (Body Control Module) fast flashes the remaining turn lamp approximately 160 times per minute to indicate a bulb outage to the driver.

The multifunction switch is a momentary contact switch, with 2 detents for the left turn position and 2 detents for the right turn position. When placed in the first detent and released, the corresponding turn signals flash 3 times and turn off. When the multifunction switch is moved to the second detent and released, the turn signal flashes until the steering wheel is turned in the opposite direction (based on input from the steering wheel rotation sensor), the multifunction switch is moved to the second detent a second time or the vehicle travels farther than 3.22 km (2 mi). The BCM (Body Control Module) monitors the steering wheel rotation sensor and the multifunction switch input to determine when to cancel the turn signals. The BCM (Body Control Module) monitors the distance traveled to determine if the turn signal should be turned off.

The BCM (Body Control Module) also provides an overload protection of the turn lamp output circuits. When an excessive current draw is detected, the BCM (Body Control Module) disables the affected turn lamp circuit driver. REFER to Field Effect Transistor (FET) Protection.

Hazard Lamps

The BCM (Body Control Module) sends a voltage signal to the FCIM (Front Controls Interface Module) to monitor for a hazard lamp function request. When the hazard flasher switch (a capacitive touch switch) is touched, the voltage signal is routed to ground, indicating a request to activate or deactivate the hazard lamp function.

When the BCM (Body Control Module) receives a request for the hazard lamps, the BCM (Body Control Module) supplies on/off voltage to all the turn lamps.

The timed on/off cycle for the hazard lamps is approximately 80 times per minute regardless of bulb outage.