Emergency call system, function

P82.95-3059-79

Function requirements, emergency call system, general

 Circuit 30

 Transport mode not active

 Each vehicle-related service is authorized separately.

 The communication module of the emergency call system control unit is configured with the telephone number of the relevant service provider.

 The vehicle owner is registered and authorized at the Service Center.

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 head unit. 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 telematics services communications module receives the "Circuit 15R" message from the electronic ignition lock control unit via the diagnostic CAN, the module checks the operational readiness of the emergency call system. After a successful check, the emergency call system is operational and "SOS ready" appears on the Audio/COMAND display. The following checks are carried out:

 Receipt of cyclic readiness signal ("sign of life") from the Supplemental Restraint System control unit

 Connection to communications module/stationary heater antenna

 Connection to GPS antenna

 In the event of a fault, depending on the fault type, a fault message appears on the Audio/COMAND display and is stored in the fault memory of the telematics services communications module.

The emergency call system function comprises the following subfunctions:

 Emergency call system status indication

 Voice connection between vehicle and Service Center

 Position finding

 Manual or automatic emergency call

Further telematics services are implemented via the emergency call system and are described in a separate document:

 Additional telematics services function

Emergency call system status indication

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

 Status indication via light-emitting diode

 Status indication on the Audio/COMAND display

Status indication via light-emitting diode

The LED of the SOS button is used to indicate the following states:

 Self-diagnosis of emergency call system, LED lights up for approx. 5 s.

 Active service, light-emitting diode flashes.

 Fault in emergency call system, LED on permanently.

 Emergency call system ready for operation, LED is off.

 Diagnosis

The telematics services communications module actuates the light-emitting diode in the SOS button via the following route:

Diagnostic CAN 

Electronic ignition lock control unit 

Interior CAN 

Front SAM control unit 

Roof LIN 

Overhead control panel control unit

Status indication on the Audio/COMAND display

The status of the emergency call system is indicated by a text message on the audio/COMAND display in the following cases:

 Emergency call system ready for operation ("SOS ready" in the "Telephone" menu)

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

 Fault in emergency call system

The telematics services communications module forwards the display via the following route:

Diagnostic CAN 

Electronic ignition lock control unit 

User interface CAN 

Head unit 

LVDS line 

Audio/COMAND display

Voice connection between vehicle and Service Center

Once the emergency call has been triggered, the telematics services communications module sets up a voice connection with the Mercedes-Benz Service Center via the communications module/stationary heater antenna.

 The setup of a voice connection to the Mercedes-Benz Service Center is aborted after several unsuccessful dialing attempts, and a corresponding message appears on the audio/COMAND display.

The telematics services communications module transmits a signal for muting the audio sources to the following component, which actuates the speaker system:

 Sound system amplifier control unit (with code 810 (Sound system))

 Head unit (except CODE 810 (Sound system))

The hands-free system is not available for telephone calls throughout the duration of the emergency call.

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 carries out the call in the language that was selected in the system settings of the head unit and transmitted in the data telegram. The hands-free system microphone, which is integrated into the inside rear-view mirror (A67), is used for voice commands.

The telematics services communications module receives the outgoing voice signals via the hands-free system microphone and then via the head unit.

The telematics services communications module outputs the incoming voice signals via the center instrument panel speaker.

The volume of the voice output can be adjusted using the following controls:

 Right multifunction steering wheel button group

 Volume control button in right lower control panel (automatic transmission) or in left lower control panel (manual transmission)

 Audio/COMAND control panel

 Touchpad (up to 31.05.2015 with code 522 (Audio 20 radio), with code 531 (COMAND APS); as of 01.06.2015 with code 448 (Touchpad))

The signals from the right multifunction steering wheel button group are sent as follows:

Steering wheel electronics 

Steering LIN 

Steering column tube module control unit 

Chassis FlexRay 

Electronic ignition lock control unit 

User interface CAN 

Instrument cluster 

User interface CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

The volume settings made on the volume control button in the lower control panel at the right or left are sent as follows:

LCP LIN 

Audio/COMAND control panel 

Telematics CAN 

Head unit 

User interface CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

The signals from the Audio/COMAND control panel or the touchpad (up to 31.05.2015 with code 522 (Audio 20 radio), with code 531 (COMAND APS); as of 01.06.2015 with code 448 (Touchpad)) are sent as follows:

Telematics CAN 

Head unit 

User interface CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

Position finding

For position finding, the telematics services communications module uses the satellite supported global navigation system (GPS) position finding system. GPS is available worldwide. GPS position finding is irretrievable 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. A basic position finding routine runs in parallel to the GPS position finding routine that makes it possible to also locate the position of the vehicle if GPS reception fails.

The position finding function consists of the following component functions:

 GPS position finding

 Basic position finding

GPS position finding

The head unit receives the GPS signal from the GPS antenna and forwards it directly to the telematics services communications module.

On vehicles with code 520 (Audio 20 USB) the telematics services communications module receives the GPS signal directly from the GPS antenna.

Additional function requirement for basic position finding

 Circuit 15R ON

Basic position finding

The telematics services communications module requires the following signals for basic position finding:

 Wheel speed and yaw rate signals from the Electronic Stability Program control unit

 Steering wheel angle sensor

The Electronic Stability Program control unit sends the wheel speed and yaw rate signals as follows:

Chassis FlexRay 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

The steering wheel angle sensor sends the signal as follows:

Steering column tube module control unit 

Chassis FlexRay 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

The telematics services communications module uses the data to calculate the current vehicle position (longitude and latitude).

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

 Model 205
up to model year 2017
with code 350 (Ecall emergency call system, Europe)
with code 355 (Preinstallation for retrofitting navigation system)
except code 347 (Mercedes-Benz emergency call system)
except code 348 (Emergency call/assistant system)
Model 205
up to model year 2017
with code 350 (Ecall emergency call system, Europe)
with code 531 (COMAND APS)
except code 347 (Mercedes-Benz emergency call system)
except code 348 (Emergency call/assistant system)
Model 253
up to model year 2017
with code 350 (Ecall emergency call system, Europe)
with code 355 (Preinstallation for retrofitting navigation system)
except code 348 (Emergency call/assistant system)
Model 253
up to model year 2017
with code 350 (Ecall emergency call system, Europe)
with code 531 (COMAND APS)
except code 348 (Emergency call/assistant system)
The telematics services communications module receives not only GPS signals but also other positioning data from the head unit, which also support basic position finding.

Manual or automatic emergency call

In an emergency situation, a service receptionist from the Mercedes-Benz Service Center can obtain an overview of the status inside the vehicle with the aid of the data received from the emergency call system 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

 Transmission of the emergency call data and communication with the Mercedes-Benz Service Center

Additional function requirements for triggering an automatic emergency call

 Circuit 15R ON

Triggering of an automatic emergency call

In the event of an accident with airbag deployment, an automatic emergency call is immediately sent out. An emergency call is sent out regardless of the severity of the accident.

The supplemental restraint system control unit sends the crash information, including the crash level as follows:

User interface CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

 The supplemental restraint system control unit transmits a readiness signal cyclically (e.g. every 500  ms) via the same route as crash information. In this way, the telematics services communications module monitors the communication with the Supplemental Restraint System control unit and the correct operation of the crash detection.

An automatic emergency call is also triggered (redundant) if the telematics services communications module receives the "central locking emergency opening" signal and at the same time the cyclic readiness signal ("sign of lift") from the supplemental restraint system control unit is not received.

The "Emergency opening of the central locking" signal is sent by the front SAM control unit as follows:

Interior CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

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 signal of the SOS button is transmitted via the following route:

Overhead control panel control unit 

Roof LIN 

Front SAM control unit 

Interior CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

Transmission of the emergency call data and communication with the Mercedes-Benz Service Center

Once a manual or automatic emergency call has been triggered, the telematics services communications module sets up a voice connection with the Mercedes-Benz Service Center. Audio sources are muted, and existing telephone connections are interrupted. The status of the connection setup is indicated by the following messages on the audio/COMAND display:

 "Activating" (setting up the call)

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

 "Connected" (voice connection established)

As soon as a connection to the Mercedes-Benz Service Center is established, the telematics services communications module automatically transmits two SMS messages using Message Access Profile (MAP). The text messages contain the following information:

 Time stamp

 GPS position (global navigation system) of the vehicle

 Language

 Vehicle identification number

 MB Contact status (ON or OFF)

Once the text messages have been transmitted, the voice connection is set up. The telematics services communications module first transmits a shortened data telegram using the dual tone multiple frequency (DTMF) via the voice connection. Then the user is contacted by a service receptionist from the Mercedes-Benz Service Center.

 During an automatic emergency call, the accept/terminate phone call button on the multifunction steering wheel is temporarily disabled while the connection is being set up in order to avoid unintentional termination. Pressing the Accept/terminate phone call button 2 times briefly in succession can interrupt the automatic emergency call.