Electronic Pedestrian Protection Impact Sensor - Operation

ELECTRONIC PEDESTRIAN PROTECTION

The acceleration-type Electronic Pedestrian Protection (EPP) 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 microcontroller in the Electronic Pedestrian Protection Module (EPPM).

The EPPM microcontroller continuously monitors all of the EPP system electrical circuits to determine the system readiness. If the EPPM detects a monitored system fault, it sets a Diagnostic Trouble Code (DTC). The ORC continually monitors the EPPM and, when it detects that the EPPM has logged a DTC, it sends electronic request messages over the CAN data bus to the Instrument Cluster (IC) (also known as the Common Instrument Cluster/CIC) to turn ON the airbag indicator. The EPPM also stores a DTC after the fault has been resolved. The impact sensors each receive battery current and ground through the dedicated left and right sensor plus and minus circuits from the EPPM. The impact sensors and the EPPM communicate by modulating the voltage in the sensor plus circuit.

The hard wired circuits between the acceleration-type EPP impact sensors and the EPPM may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. 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 EPP system. The most reliable, efficient, and accurate means to diagnose the impact sensors or the electronic controls and communication related to acceleration-type EPP impact sensor operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.