Emergency call system, function

 On vehicles as of 01.09.2015 (model year 2016) there are two chassis CAN variants.
Variant 1:
If the vehicle does not contain any of the equipment codes specified in variant 2, then, as before, only one chassis CAN (CAN E) is available.
Version 2:
If the vehicle has one of the following equipment codes, then one chassis CAN 1 (CAN E1) and one chassis CAN 2 (CAN E2) is available:

 Code 218 (Reversing camera)

 CODE 234 (Blind Spot Assist)

 Code 459 (Steel suspension with adjustable damping)

 Code 475 (Tire pressure monitor)

 Code 476 (Lane Keeping Assist)

 Code 513 (Speed Limit Assist)

 CODE 614 (Bi-xenon headlamp)

 CODE 615 (Bi-xenon headlamp with active curve lights)

 CODE 618 (Bi-xenon headlamp)

 Code 621 (Intelligent Light System (left-hand traffic))

 Code 622 (Intelligent Light System)

 Code 631 (Static LED headlamps for left-hand traffic system)

 Code 632 (Static LED headlamps for right-hand traffic system)

The differences between variant 1 and variant 2 are explained in the following text.

P82.70-7743-79

P82.70-7766-79

Function requirements, emergency call system, general

 Circuit 30

 Transport mode is inactive.

 The telematics services communications module 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. Where possible, the user is addressed in the language that is selected in the system settings of the audio equipment. If necessary, the Mercedes-Benz Service Center notifies the local rescue services. If the Mercedes-Benz Service Center cannot be reached, the emergency call is automatically forwarded to the local rescue services 112.

If the telematics services communications module receives the message "Circuit 15" from the electronic ignition lock control unit over 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 for muting audio sources

 Connection to hands-free system microphone group, over the audio equipment

 Connection to emergency call system antenna

 Connection to GPS antenna (model 246, 242, 156, 176 with CODE 505 (Radio 20 NTG5 non-navigation capable), with CODE 520 (Audio 20 USB)) or to the multifunction antenna (model 117.3 with CODE 505 (Radio 20 NTG5 non-navigation capable), with CODE 520 (Audio 20 USB))

 In the event of a fault, the message "SOS NOT READY" appears on the Audio/COMAND display and the fault code is stored in the fault memory of the telematics services communications module. If, after switching off the ignition, the Supplemental Restraint System control unit switches to the "Sleep" mode, it no longer sends a readiness signal and the "SOS NOT READY" message is also shown.

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

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 in instrument cluster

Status indication via light-emitting diode

The LED of the emergency call system button is used to indicate the following status:

 Active service, light-emitting diode flashes.

 Diagnosis

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

Diagnostic CAN 

Electronic ignition lock control unit 

Interior CAN 

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 operational ("SOS READY" in "Telephone" menu) or not operational ("SOS NOT READY" in "Telephone" menu)

 Emergency call triggered ("activating", "sending data" (only visible when the SMS transmission takes unusually long), "connected" (MB emergency call connected))

 Emergency call forwarded to local 112 rescue services (the address (with code 531 (COMAND APS)) and the coordinates of the vehicle position are also shown)

 Fault in emergency call system

If an emergency call is active, the top right of the Audio/COMAND display also shows a telephone symbol, an emergency call symbol and the field strength of the telematics services communications module.

The telematics services communications module sends the display over the following channel:

Diagnostic CAN 

Electronic ignition lock control unit 

Interior CAN 

Audio equipment 

LVDS line 

Audio/COMAND display

Some text messages on the Audio/COMAND display can be confirmed. Confirmation is made on the Audio/COMAND control panel. The Audio/COMAND control panel sends the signals via the following route:

Telematics CAN 

Audio equipment 

Interior CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

Status indication in instrument cluster

If the telematics services communications module fails, the instrument cluster displays "SOS nonfunctional". The failure is reported over the following path:

Diagnostic CAN 

Electronic ignition lock control unit 

Interior CAN 

Instrument cluster

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 emergency call system antenna.

 The activation of a voice connection to the Mercedes-Benz Service Center is canceled after several failed attempts to connect, and the following message is shown on the Audio/COMAND display: "MB emergency call activation failed. Please dial 112 on the mobile phone."

On vehicles with CODE 810 (Sound system) the telematics services communications module sends a signal to mute the audio sources to the sound system amplifier control unit. The sound system amplifier control unit then stops playback of the audio signals that it receives via MOST.

On vehicles except CODE 810 (Sound system) the telematics services communications module sends a signal to mute the audio sources to the audio equipment. The audio equipment then stops playback of the audio signals.

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 audio equipment and transmitted in the data telegram. The hands-free system microphone is used for the voice input.

The telematics services communications module receives the outgoing voice signals from the hands-free system microphone through the audio equipment.

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

 Audio unit

The right multifunction steering wheel button group sends the control signals via the following route:

Steering wheel electronics 

Steering LIN 

Steering column tube module control unit 

Variant 1:

Chassis CAN 

Version 2:

Chassis CAN 1 

Electronic ignition lock control unit 

Chassis CAN 2 

Instrument cluster 

Interior CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

The audio equipment sends the volume setting signals over the following route:

Interior CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

Position finding

The telematics services communications module uses the satellite-supported global positioning system (GPS) to find its location. GPS is available worldwide. GPS position finding is irretrievable after vehicle transport (e.g. by train or ferry or after towing). Subsequent GPS position finding (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

On vehicles with code 522 (Audio 20 radio) or with code 531 (COMAND APS), the audio equipment receives the GPS signal from the GPS antenna (except model 117.3) or from the multifunction antenna (model 117.3) and forwards it as follows:

Interior CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

On vehicles with CODE 505 (Radio 20 NTG5 non-navigation capable) or with CODE 520 (Audio 20 USB), the telematics services communications module receives the GPS signal from the GPS antenna (except model 117.3) or from the multifunction antenna (model 117.3).

Additional function requirement for basic position finding

 Circuit 15 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:

Variant 1:

Chassis CAN 

Version 2:

Chassis CAN 1 

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 

Variant 1:

Chassis CAN 

Version 2:

Chassis CAN 1 

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).

 Location errors in position finding, 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 117.3 as of 11/3/14, 242 as of 11/3/14, 246 as of 11/3/14
as of model year 2015 up to model year 2017
with code 350 (Ecall emergency call system, Europe)
with code 357 (Map navigation)
except code 348 (Emergency call/assistant system)
Model 117.3 as of 11/3/14, 242 as of 11/3/14, 246 as of 11/3/14
as of model year 2015 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)
Model 117.9
up to model year 2017
with code 350 (Ecall emergency call system, Europe)
with code 357 (Map navigation)
Model 117.9
up to model year 2017
with code 350 (Ecall emergency call system, Europe)
with code 531 (COMAND APS)
Model 156 as of 9/1/15
as of model year 2016 up to model year 2017
with code 350 (Ecall emergency call system, Europe)
with code 357 (Map navigation)
except code 348 (Emergency call/assistant system)
Model 156 as of 9/1/15
as of model year 2016 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)
Model 176 as of 9/1/15
as of model year 2016 up to model year 2017
with code 350 (Ecall emergency call system, Europe)
with code 357 (Map navigation)
Model 176 as of 9/1/15
as of model year 2016 up to model year 2017
with code 350 (Ecall emergency call system, Europe)
with code 531 (COMAND APS)
The audio equipment not only sends GPS signals to the telematics services communications module, but also additional position data that likewise supports 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 telematics services communications module (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 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 is immediately sent. An emergency call is sent out regardless of the severity of the accident. The telematics service communications module receives the crash information over a direct line as a digital crash signal from the Supplemental Restraint System control unit.

The supplemental restraint system control unit also (redundantly) sends the crash information, including crash level, via the following route:

Variant 1:

Chassis CAN 

Version 2:

Chassis CAN 1 

Electronic ignition lock control unit 

Diagnostic CAN 

Telematics services communication module

 The supplemental restraint system control unit transmits a readiness signal cyclically via the same route (e.g. every 500 ms). 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 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 emergency call system button. The emergency call system button is covered up with a locking flap. Pressing the protective lid unlocks the lid, and it automatically opens with the aid of a spring mechanism.

The emergency call system button signals are sent as follows:

Overhead control panel control unit 

Roof LIN 

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", "Sending data" , "Connected")

 "Sending data" (only visible when the SMS message takes unusually long to send)

 "Connected" (MB emergency call connected)

As soon as a connection to the Mercedes-Benz Service Center is established, the telematics services communications module automatically sends two SMS messages with the following data to the Service Center:

 Time stamp

 Global Positioning System (GPS) position of vehicle

 Language

 Vehicle identification number

 MB Contact status (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 the SMS have been sent, the voice connection is activated and the user is addressed by a service receptionist at 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.