Forward Collision Alert Description and Operation: Notes

The forward collision alert system is a convenience feature of the frontview camera module that issues a warning to the driver when a potential collision risk exists. The frontview camera module is located behind the windshield, looking out at the road ahead and detecting vehicles directly ahead, within a distance of approximately 60 m (197 ft). At night or in poor conditions, the distance may be reduced to approximately 40 m (130 ft). The forward collision alert system is always active and operates at speeds above 40 kph (25 mph).

When the frontview camera module detects a vehicle in the path ahead, the green vehicle ahead indicator on the collision alert indicators is illuminated. When following a vehicle ahead too closely, the red collision alert indicator on the collision alert indicators will remain illuminated until the following distance is increased. When the following distance is increased, the green vehicle ahead indicator will be illuminated again. When approaching another vehicle too rapidly, the red collision alert indicator will flash and an audible alert will sound. Forward collision alert does not warn the driver of any objects that are not detected, such as pedestrians, animals, signs, guard rails, bridges, construction barrels or other stationary or slow moving objects. The forward collision alert timing sensitivity can be set using the forward collision alert switch, located in the steering wheel controls switch - left.

In some cases, the camera may detect a vehicle that is not in the path ahead or the system may occasionally provide unrealistic alerts. This may be in response to a turning vehicle ahead, vehicles in other lanes, objects that are not vehicles, guard rails, traffic signs, shadows or other stationary objects. This is normal operation and the vehicle does not require service.

The forward collision alert system is made up of the following components:

• Frontview camera module
• Forward collision alert switch, part of the steering wheel controls switch - left
• Collision alert indicators, controlled by the instrument cluster
• Radio

Front View Camera Module 

The frontview camera module detects vehicles in front of the host vehicle. The frontview camera module communicates via serial data to the instrument cluster to illuminate the appropriate indicators on the collision alert indicators. The frontview camera module also communicates via serial data with the radio to request audible alerts.

Forward Collision Alert Switch 

The forward collision alert switch provides an input to the frontview camera module to select different alert timing sensitivity settings. This setting will change the sensitivity for both the following too closely indicator and the forward collision alert indicators. In addition to the sensitivity setting, the alert distance will change based upon vehicle speed.

The frontview camera module provides a signal voltage to the normally open momentary forward collision alert switch. When the switch is not pressed, the signal circuit is effectively open and voltage observed by the frontview camera module is high. When the switch is pressed, the signal circuit is pulled to ground through a resistor, reducing the voltage observed by the frontview camera module. This will indicate to the frontview camera module that the system has been requested to change the alert timing sensitivity. The first button press will show the current alert timing setting on the driver information center. With every subsequent button press, the alert timing sensitivity is changed.

Collision Alert Indicators 

The collision alert indicators contains the indicators for the collision alert system and are controlled by the instrument cluster via serial data messages from the frontview camera module. When the green vehicle ahead indicator is illuminated, the system has detected a vehicle in the driving path ahead. The red collision alert indicator will illuminated continuously if the system determines that the vehicle ahead is too close. When approaching another vehicle too rapidly, the red collision alert symbol will flash.

Voltage is applied to the collision alert indicators by the body control module (BCM) at all times. The instrument cluster controls each indicator by providing a controlled ground. When the control circuit ground grounded by the instrument cluster, the indicator will be illuminated. The collision alert indicators also contain the lane departure warning indicators.

Radio 

The radio controls the audible alert for the forward collision alert system and is activated via serial data from the frontview camera module. If the vehicle is approaching another vehicle too rapidly, the radio will provide an audible alert to the driver, as requested by the frontview camera module.