Turn Signals

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

When the BCM  receives a request for a turn signal, the BCM  supplies on/off voltage to the appropriate turn lamps.

The timed on/off cycle for turn lamps is determined by the BCM  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  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  monitors the steering wheel rotation sensor and the multifunction switch input to determine when to cancel the turn signals. The BCM  monitors the distance traveled to determine if the turn signal should be turned off.

The BCM  also provides an overload protection of the turn lamp output circuits. When an excessive current draw is detected, the BCM  disables the affected turn lamp circuit driver. REFER to MULTIFUNCTION ELECTRONIC MODULES .