Front Impact Sensor
Front Impact Sensor
Description
Two acceleration type front impact sensors (1) are used on this vehicle, one each for the left and right sides of the vehicle. These sensors are mounted remotely from the impact sensor that is internal to the occupant restraint controller. Each front sensor is secured with a screw to the back of the front end module carrier on either side of the cooling module, just below the inboard end of each front lamp unit housing within the engine compartment. The sensor housing has an integral connector receptacle (3), an integral locating and anti-rotation pin, and an integral mounting hole (2).
The right and left front impact sensors are identical in construction and calibration. A cavity in the center of the molded plastic impact sensor housing contains the electronic circuitry of the sensor which includes an electronic communication chip and an electronic impact sensor. The cavity is filled with a potting material to seal and protect the internal electronic circuitry and components. The front impact sensors are each connected to the vehicle electrical system through a dedicated take out and connector of the front end module wire harness.
These acceleration type front impact sensors cannot be repaired or adjusted and, if damaged or ineffective, they must be replaced.
Operation
The acceleration type front impact sensors are electronic accelerometers that sense the rate of vehicle deceleration, which provides verification of the direction and severity of an impact. Each sensor also contains an electronic communication chip that allows the unit to communicate the sensor status as well as sensor fault information to the microprocessor in the ORC.
The ORC microprocessor continuously monitors all of the front passive restraint system electrical circuits to determine the system readiness. If the ORC detects a monitored system fault, it sets a diagnostic trouble code and commands the airbag indicator operation accordingly. The impact sensors each receive battery current and ground through dedicated left and right sensor plus and minus circuits from the ORC. The impact sensors and the ORC communicate by modulating the current in the sensor plus circuit.
The hard wired circuits between the acceleration type front impact sensors and the ORC may be diagnosed using conventional diagnostic tools and procedures. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the impact sensors or the electronic controls or communication between other modules and devices that provide features of the supplemental restraint system. The most reliable, efficient, and accurate means to diagnose the impact sensors or the electronic controls and communication related to acceleration-type front impact sensor operation requires the use of a diagnostic scan tool.