Circuit/System Description

The forward collision alert system is controlled by the frontview camera module mounted on the windshield. The forward collision alert system is always active and operates at speeds above 40 km/h (25 mph). When the system detects a vehicle in the path ahead, the frontview camera module will request via serial data communications that the instrument cluster illuminate the green vehicle ahead alert indicator. When approaching another vehicle too rapidly, the frontview camera module will request via serial data communications that the instrument cluster flash the red collision alert symbol and the radio will simultaneously give an audible alert sound. The red collision alert display will stay continuously illuminated if the vehicle ahead remains much too close.

The lane departure warning switch and forward collision alert switch share a single signal circuit that is monitored by the frontview camera module. The frontview camera module applies voltage and monitors the switch signal circuit. The lane departure warning switch and forward collision alert switch are both normally open switches. With both switches open, voltage seen at the frontview camera module is high. When a switch is pressed, the switch is closed and the signal circuit is pulled to ground through a specific resistor. Based on the voltage drop across the resistor, the frontview camera module can determine which switch was pressed. The frontview camera module will respond to this by activating or deactivating the lane departure warning feature or changing the forward collision alert timing sensitivity.