Emergency call system, function

D82.95-0030-79

Function requirements, general

 Circuit 30 ON

 Transport mode not active

 The communications module of the HERMES control unit is configured with the telephone number of the relevant service provider.

Emergency call system, general

The emergency call system allows a manual or automatic emergency call to be triggered. The emergency call is received by the Mercedes-Benz Service Center. The user is spoken to in the language that is selected in the system settings of the instrument cluster or head unit.

 On vehicles with one of the following items of equipment, the language selected in the instrument cluster is decisive:

 CODE ER0 (Radio preinstallation)

 Code E1O(Entrance radio)

 On vehicles with one of the following items of equipment, the language selected in the head unit is decisive:

 Code E1A (MBCONNECT-5)

 Code E1C (Audio 25)

 Code EJ9 (COMAND Online)

If necessary, the Mercedes-Benz Service Center notifies the local rescue services. If the Mercedes-Benz Service Center is not staffed, the emergency call is automatically forwarded to the local rescue services.

If the HERMES control unit receives the message "Terminal 15" from the electronic ignition lock (EZS) control unit via the diagnostics CAN, it checks the operational readiness of the emergency call system. After a successful check, the emergency call system is operational and "SOS ready" is shown on the Audio/COMAND display control unit. The following checks are carried out:

 Reception of cyclic readiness signal ("sign of life") from the supplemental restraint system (SRS) control unit

 Connection for muting audio sources

 Connection to microphone, emergency call system microphone

 Communications module/stationary heater antenna

 Roof antenna

 GSM antenna

 In the event of a fault, depending on the fault type, a fault message appears on the Audio/COMAND display control unit and the fault is stored in the fault memory of the HERMES control unit. If, after switching off the ignition, the supplemental restraint system (SRS) control unit goes into sleep mode, it no longer sends a readiness signal and "SOS not ready" is shown.

The electronic ignition lock (EZS) control unit transmits the status of terminal 15 to the HERMES control unit via the diagnostics CAN.

The emergency call system function includes the following subfunctions:

 Emergency call system status indication

 Position finding

 Manual or automatic emergency call

Emergency call system status indication

The status of the emergency call system is shown in the following ways:

 Status indication on the Audio/COMAND display control unit

 Status indication via light-emitting diode

 Status indication in instrument cluster

Status indication on the Audio/COMAND display control unit

The status of the emergency call system is shown by a text message in the Audio/COMAND display control unit in the following cases:

 Emergency call system operational or not operational ("SOS ready" or "SOS not ready" in telephone menu)

 Emergency call has been activated ("activating" (call setup), "transmitting data" (data telegram transmission), "connected" (voice connection established))

 Emergency call forwarded to local 112 rescue services (the address and coordinates of the vehicle position are also shown)

 Call activation has failed several times ("MB emergency call setup unsuccessful. ", "Please dial 112 on the mobile phone.")

In the event of an active emergency call, a telephone symbol, an emergency call symbol and the field strength of the HERMES control unit are also shown on the Audio/COMAND display control unit at the top right.

The HERMES control unit sends the information to the head unit for display. This sends a switch-on request and the picture data over the telematics CAN to the Audio/COMAND display control unit.

Status indication via light-emitting diode

 Active service, light-emitting diode flashes.

 Self-diagnosis of emergency call system, light-emitting diodes on for approx. 5 s.

 Fault in emergency call system, LEDs permanently on.

 Diagnosis

The HERMES control unit sends the request to switch on the light-emitting diode to the overhead control panel (OCP) control unit. This actuates the LED in the SOS button.

Status indication in instrument cluster

If the HERMES control unit fails, the message "SOS nonfunctional" is displayed in the instrument cluster. To do this, the HERMES control unit constantly sends the system status to the instrument cluster.

Position finding

Position finding is performed by the HERMES control unit. For position finding, the HERMES control unit uses the global navigation system (GPS). GPS is available worldwide. GPS position finding is required after vehicle transport (e.g. by train or ferry or after towing). Recalculation of the GPS position (following an interruption in satellite reception) can take several minutes. At the same time as the GPS position finding the HERMES control unit conducts a permanent basic position finding, that enables the position of the vehicle to be determined even when the GPS reception fails.

Additional function requirement for basic position finding

 Circuit 15 on

Basic position finding

The HERMES control unit requires the following signals for basic position finding:

 Wheel speed and yaw rate signals from the ESP® control unit

 Steering wheel angle signal from the steering column tube module (MRM) control unit

The ESP® control unit sends the wheel speed and yaw rate signals to the HERMES control unit.

The steering column tube module (MRM) control unit sends the signals from the steering wheel angle sensor to the HERMES control unit.

The HERMES control unit uses the data to calculate the instantaneous position of the vehicle (longitude, latitude and direction of travel).

 Location errors in position finding, rolling backwards with "Terminal 15 OFF" (ignition switched off) or vehicle transportation falsify the basic position finding. In both cases, this deviation is automatically corrected on receipt of GPS data.

Manual or automatic emergency call

In an emergency situation, a service receptionist from the Mercedes-Benz Service Center can obtain an overview of the condition inside the vehicle with the aid of the data received from the HERMES control unit (voice connection and data telegram) and initiate appropriate help measures. An emergency call be initiated manually or automatically. These emergency calls are made for the following reasons:

 Automatic alerting of the rescue services after an accident

 Alerting rescue services by pushing a button (own emergency situation, observed accident)

 Reduction in rescue times through fast emergency notification with details on exact location involved

 The automatic emergency call has priority over a manually triggered emergency call. If an automatic emergency call is triggered during a manual emergency call, the manual emergency call is interrupted. If a manual emergency call is triggered during an automatic emergency call, it is ignored. However, a data telegram containing updated position data is sent to the Mercedes-Benz Service Center, and the existing connection is maintained.

The manual or automatic emergency call function consists of the following subfunctions:

 Triggering of an automatic emergency call

 Triggering of a manual emergency call

 Voice connection between vehicle and Service Center

Additional function requirements for triggering an automatic emergency call

 Circuit 15 on

Triggering of an automatic emergency call

In the event of an accident with deployment of the restraint systems (not the PRE-SAFE® system) an automatic emergency call (E-call) is immediately sent. An emergency call is sent out regardless of the severity of the accident.

The HERMES control unit receives the crash information over the seat occupancy LIN as a digital crash signal from the supplemental restraint system (SRS) control unit.

The supplemental restraint system (SRS) control unit also (redundantly) sends the crash information, including crash level, to the HERMES control unit.

 The supplemental restraint system control unit sends a readiness signal cyclically (e.g. every 500 ms) over the same path. The HERMES control unit thereby monitors communication with the supplemental restraint system (SRS) control unit and the proper function of the crash detection.

Additional function requirements for triggering a manual emergency call

 No automatic emergency call is active.

Triggering of a manual emergency call

The manual emergency call is triggered by pressing the SOS button. The emergency call system button is covered up with a locking flap. Pressing the protective flap unlocks the flap, and it opens automatically with the aid of a spring mechanism.

The overhead control panel (OCP) control unit sends the status of the SOS button to the HERMES control unit.

Voice connection between vehicle and Service Center

Once the emergency call has been triggered, the HERMES control unit establishes an audio communication to the Mercedes-Benz Service Center via the antennas.

The status of the connection setup is displayed on the Audio/COMAND display control unit through the following messages:

 "Activating" (setting up the call)

 "Transmitting data" (transmission of emergency call data (data telegram))

 "Connected" (voice connection established)

 Establishing a voice connection to the Mercedes-Benz Service Center is aborted after several unsuccessful dialing attempts. The following message is then shown on the Audio/COMAND display control unit: "MB emergency call activation failed." "Please dial 112 on the mobile phone.".

 During an automatic emergency call, the accept/terminate phone call button (S163/2s3) on the multifunction steering wheel is temporarily disabled while the connection is being established. This prevents any unintentional termination.

While the connection is being set up, audio sources are muted (mute function) and existing telephone connections are interrupted.

As soon as a connection is set up to the Mercedes-Benz Service Center, the HERMES control unit automatically sends a data telegram to the Service Center. The data telegram transmits the following data:

 Time stamp

 GPS position of vehicle

 Language

 Vehicle identification number

 Status of Mercedes-Benz Contact (ON or OFF)

 Position history (Tracing of vehicle positions up to a distance of a few 100  m from current location)

 Number of vehicle occupants (estimated)

After a data telegram has been transmitted to the Mercedes-Benz Service Center, the user can speak to a service receptionist via the voice connection. The Mercedes-Benz Service Center conducts the call, where possible, in the language that was selected in the system settings of the instrument cluster or the head unit and sent in the data telegram. The emergency call system microphone, which is installed on the driver side of the roof interior trim, is used here for voice input.

The HERMES control unit receives outgoing voice signals from the emergency call system microphone by way of the head unit.

The HERMES control unit emits the incoming voice signals through the center instrument panel mid-range speaker.

The voice output volume can be adjusted using the instrument cluster multifunction steering wheel button group.

The steering wheel electronics reads the control signals directly. The steering column tube module (MRM) control unit reads them in over the steering wheel LIN and sends them to the instrument cluster. The instrument cluster sends the control signals of the instrument cluster multifunction steering wheel button group to the HERMES control unit.

 With a manual or an automatic emergency call, the Service Center can transfer the map data to the vehicle if required. The data is made available to the navigation module of the head unit.