Exterior Lighting - System Operation and Component Description

The timed on/off cycle for turn lamps is determined by the BCM and is set to flash approximately 70 times per minute if both the front and rear turn signal lamps operate correctly.

The rear turn lamps are Light Emitting Diodes (LEDs) in the rear lamp assemblies and have an outage circuit that tells the Body Control Module (BCMB) when the Light Emitting Diodes (LEDs) are inoperative. During normal operation, when voltage is applied to the rear turn Light Emitting Diodes (LEDs), the feedback circuit sends the same voltage back to the Body Control Module (BCMB) through the outage circuit. If the Light Emitting Diodes (LEDs) are inoperative the Body Control Module (BCMB) will not receive this voltage feedback through the outage circuit.

If a front or rear turn signal lamp is inoperative, the BCM fast flashes the remaining turn lamp(s) approximately 150 times per minute to indicate a bulb outage to the driver.

The LH steering column multifunction switch has 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 LH steering column multifunction switch is moved to the second detent, the turn signal flashes until the steering wheel is turned in the opposite direction.

The BCM Body Control Module (BCMB) and also provide an Field Effect Transistor (FET) protection of the stoplamp output circuits. When an excessive current draw is detected, the BCM or Body Control Module (BCMB) disable the affected stoplamp circuit driver.

Refer to: Module Controlled Functions - System Operation and Component Description (419-10 Multifunction Electronic Modules, Description and Operation).

Hazard Lamps

The BCM sends a voltage signal to the hazard flasher lamp switch (integrated into the FCIM) to monitor for a hazard lamp function request. When the hazard flasher lamp switch is pressed, the voltage signal is routed to ground, indicating a request to activate or deactivate the hazard lamp function.

When the BCM receives a request for the hazard lamps, it activates all the turn signal lamps.

The timed on/off cycle for the hazard lamps is approximately 70 times per minute, regardless of bulb outage.

Turn Signal and Hazard Lamps - China Only

System Diagram

Network Message Chart