Theory Of Operation

The Emergency Assistance Module (EAM) incorporates a backup battery with a life expectancy of 5-7 years that will allow the emergency call (eCall) to a Public Safety Answering Point (PSAP) system to continue to work in case of vehicle power interruption. The battery will allow call and data transfer for at least 15 minutes with callback capability for at least one hour after a vehicle emergency. The eCall system uses a single dedicated 70mm speaker for vocal communication with the vehicle occupants during an eCall.

The EAM system will detect an eCall trigger, whether automatic through a crash severe enough or manual at a vehicle occupant's request by pressing the SOS button. Once triggered, the system will attempt to send an MSD to any public system operated by an MNO and also attempt to establish a voice connection between the vehicle and the PSAP. When connected to the MNO, the vehicle will transfer the vehicle location and VIN.

The EAM system is triggered automatically when the Occupant Restraint Controller (ORC) sends a signal using the Controller Area Network (CAN) - C data bus and / or the Output Digital Serial line. The severity of the crash will determine if an eCall is sent or not. This will include direction of the impact, whether frontal, side, rear or rollover. The EAM system can be manually triggered using the SOS button by the vehicle driver or a passenger. The EAM will actuate the system in the same manner as if it had been triggered automatically by the ORC. When eCall is in operation, the Radio audio will be muted and eCall audio will be heard through the eCall speaker.

The hard wired inputs and outputs for the EAM 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 EAM or the electronic controls and communication between other modules and devices that provide some features of the EAM system. The most reliable, efficient and accurate means to diagnose the EAM or the electronic controls and communication related to EAM system operation requires the use of a diagnostic scan.

In the event that the vehicle battery connection is compromised, a backup battery is mounted within the EAM to ensure the integrity of the system and a continuation of an eCall if the vehicle battery becomes disconnected while a call is in progress. If the backup battery becomes discharged, a message will be indicated in the Instrument Panel Cluster (IPC) and a diagnostic code set in the EAM. The EAM microcontroller continuously monitors all of the EAM system electrical circuits to determine the system readiness. If the EAM detects a monitored system fault, it sets an active and stored Diagnostic Trouble Code (DTC) and sends electronic messages to the IPC and BCM over the CAN data bus to turn On the EAM indicator. An active fault only remains for the duration of the fault, or in some cases for the duration of the current ignition cycle, while a stored fault causes a DTC to be stored in memory by the EAM.