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 within 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) and notifies the Occupant Restraint Controller (ORC). The ORC then sends electronic messages to the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) to control the airbag indicator operation accordingly. 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 and 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.