With Electronic Pedestrian Protection System
In vehicles so equipped, a microcontroller within the Occupant Restraint Controller (ORC) also contains the Electronic Pedestrian Protection (EPP) system (also known as the PedPro or the Active Hood System) logic circuits. The EPP system logic of the ORC continuously monitors the three dedicated EPP acceleration-type electronic impact sensors located behind the front bumper area of the fascia at the front of the vehicle. The impact sensors are accelerometers that sense the rate of vehicle deceleration, which provides verification of the direction and severity of an impact.
The ORC also monitors electronic ignition status , vehicle speed and ambient temperature message inputs received from other electronic modules over the Controller Area Network (CAN) data bus. The EPP system logic of the ORC uses a pre-programmed decision algorithm to analyze all of these inputs, which allows the ORC to determine both the type and severity of an impact.
When the deceleration rate as signaled by the impact sensors indicate an impact that requires an EPP deployment and all other programmed conditions are met, the ORC sends the proper electrical signals to deploy the actuators. A pyrotechnic EPP actuator is located on each active hood hinge at the rear corners of the hood panel. As a safing function, the ORC requires confirming sensor inputs from at least two of the three EPP impact sensors before it will issue a deployment signal.
The ORC also contains an energy-storage capacitor. When the status of the ignition switch is Start or On this capacitor is continually being charged with enough electrical energy to deploy the active hood hinge actuators for up to one second following a battery disconnect or failure. The purpose of the capacitor is to provide backup EPP system protection in case there is a loss of battery current supply to the ORC during an impact event.
An Event Data Recorder (EDR) within the ORC stores EPP near-deployment event records. The ORC microcontroller continuously monitors all of the EPP system electrical circuits to determine the system readiness. If the ORC detects a monitored system fault, it logs an active Diagnostic Trouble Code (DTC). The ORC also stores a DTC after an active DTC has been resolved. When the ORC has logged a DTC, it sends electronic request messages over the CAN data bus to the Instrument Panel Cluster (IPC) to turn On the airbag indicator.
The hard wired EPP inputs and outputs for the ORC 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 ORC or the electronic controls and communication between other modules and devices that provide some features of the EPP system. The most reliable, efficient and accurate means to diagnose the ORC or the electronic controls and communication related to EPP system operation requires the use of a diagnostic scan tool and may also require the use of the SRS Load Tool special tool along with the appropriate Load Tool Jumpers and Adapters. Refer to the appropriate diagnostic information.