Emergency Call System, Function - GF82.95-P-0004RRA
Model 190 up to 11/30/18
as of model year 2017 up to model year 2019 With Code 351 (eCall emergency call system)
Function requirements, emergency call system, general
- Circuit 30
- Transport mode not active
- Each vehicle-related service is authorized separately.
- The communications module of the HERMES 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 112.
If the HERMES control unit receives the message "Circuit 15 R" from the electronic ignition lock control unit over the diagnostic CAN, it 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, from head unit
- Connection to emergency call system antenna
- Connection to GPS antenna
- Connection to left telephone antenna and right telephone antenna over the telephone antenna splitter (with code 362 (HERMES LTE))
In the event of a fault, depending on the fault type, a fault message appears on the Audio/COMAND display and the fault code is stored in the fault memory of the HERMES control unit. 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 shown.
The HERMES control unit receives the "Circuit 15 R" message from the electronic ignition lock control unit as follows:
Interior CAN →
Front SAM control unit with fuse and relay module →
Diagnostic CAN →
HERMES control unit
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 SOS button is used to indicate the following states:
- Active service, light-emitting diode flashes.
- Self-diagnosis of emergency call system, LED lights up for approx. 5 s.
- Fault in emergency call system, LEDs permanently on.
- Emergency call system ready for operation, LED is off.
- Diagnosis
The HERMES control unit actuates the LED in the SOS button in the overhead control panel electronics over direct lines.
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 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 (with code 531 (COMAND APS)) and the coordinates of the vehicle position are also shown)
- Call activation has failed several times ("MB emergency call processing failed. Please dial 112 on the mobile phone.")
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 HERMES control unit.
The HERMES control unit sends the display over the following path:
Diagnostic CAN →
Front SAM control unit with fuse and relay module →
Chassis CAN 1 →
AMG gateway control unit →
User interface CAN →
Head unit →
LVDS line →
Audio/COMAND display
Control communication between the head unit and Audio/COMAND display takes place via the telematics CAN.
Some text messages on the Audio/COMAND display can be confirmed using the Audio/COMAND control panel or the touchpad (with code 448 (Touchpad) or with code 531 (COMAND APS)). The Audio/COMAND control panel or the touchpad sends the signals over the following route:
Telematics CAN →
Head unit →
User interface CAN →
AMG gateway control unit →
Chassis CAN 1 →
Front SAM control unit with fuse and relay module →
Diagnostic CAN →
HERMES control unit
Status indication in instrument cluster
If the HERMES control unit fails, the instrument cluster shows "SOS nonfunctional". The failure of the HERMES control unit is reported over the following path:
Diagnostic CAN →
Front SAM control unit with fuse and relay module →
Chassis CAN 1 →
AMG gateway control unit →
User interface CAN →
Instrument cluster
Voice connection between vehicle and Service Center
After triggering the emergency call, the HERMES control unit sets up a voice connection to the Mercedes-Benz Service Center over the emergency call system antenna, as well as over the telephone antenna splitter and the left telephone antenna, right telephone antenna (with code 362 (HERMES LTE)).
Model 190 up to 11/30/18
as of model year 2017 up to model year 2019
with code 351 (eCall emergency call system)
with code 362 (HERMES communications module LTE)
To obtain transmission and reception diversity, the emergency call system antenna and the left telephone antenna, right telephone antenna are used to set up the connection.
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)
Establishing 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."
To avoid any unintentional termination, the Accept/Terminate phone call button on the multifunction steering wheel is temporarily disabled while the connection is being established during an automatic emergency call.
While the connection is being set up, audio sources are muted (mute function) and existing telephone connections are interrupted.
In vehicles except code 810 (Sound system) and except code 811 (Advanced sound system), the HERMES control unit sends the signal for the mute function to the head unit.
In vehicles with code 810 (Sound system), the HERMES control unit sends the signal for the mute function to the sound system amplifier control unit.
In vehicles with code 811 (Advanced sound system), the HERMES control unit sends the signal for the mute function to the Advanced sound system amplifier control unit.
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
- 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 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, where possible. The hands-free system microphone is used for the voice input. The hands-free system is not available for telephone calls throughout the duration of the emergency call.
The HERMES control unit receives the outgoing voice signals over the driver's hands-free system microphone from the head unit.
The HERMES control unit emits the incoming voice signals over the center instrument panel mid-range speaker (with code 810 (Sound system) or with code 811 (Advanced sound system)) or through the emergency call speaker (except code 810 (Sound system) and except code 811 (Advanced sound system)).
The volume of the voice output can be e.g. regulated using the following controls:
- The + and - button for setting specific functions and volume control of the right multifunction steering wheel button group
- On/off button with volume control
The Accept/terminate phone call button of the right multifunction steering wheel button group can be used to end the emergency call, if this is not done by the Mercedes-Benz Service Center.
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 CAN 1 →
Front SAM control unit with fuse and relay module →
Diagnostic CAN →
HERMES control unit
The volume settings from the ON/OFF button with volume control are sent as follows:
Audio LIN →
Audio/COMAND control panel →
Telematics CAN →
Head unit →
User interface CAN →
AMG gateway control unit →
Diagnostic CAN →
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.
Position finding
On vehicles with code 531 (COMAND APS) the HERMES control unit receives the position finding signals from the head unit. On vehicles with code 360 (HERMES UMTS), the head unit sends the signals over a USB line (Universal Serial Bus) to the HERMES control unit. On vehicles with code 362 (HERMES LTE), the head unit sends the signals via the WLAN antenna (with code 531 (COMAND APS)) to the HERMES control unit WLAN interface.
On vehicles with code 520 (Audio 20 USB) the position finding is conducted 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 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. 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.
The position finding function consists of the following component functions:
- GPS position finding (With Code 520 (Audio 20 USB))
- Basic position finding (With Code 520 (Audio 20 USB))
GPS position finding (With Code 520 (Audio 20 USB))
The HERMES control unit receives the GPS signal from the GPS antenna.
Additional function requirements for basic position finding (With Code 520 (Audio 20 USB))
- Circuit 15 R On
Basic position finding (With Code 520 (Audio 20 USB))
The HERMES control unit 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 signal
The Electronic Stability Program control unit sends the wheel speed and yaw rate signals as follows:
Chassis CAN 1 →
Front SAM control unit with fuse and relay module →
Diagnostic CAN →
HERMES control unit
The steering wheel angle sensor sends the signal as follows:
Steering column tube module control unit →
Chassis CAN 1 →
Front SAM control unit with fuse and relay module →
Diagnostic CAN →
HERMES control unit
The HERMES control unit uses the data to calculate the instantaneous position of the vehicle (longitude, latitude and direction of travel).
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.
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
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 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 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:
Chassis CAN 1 →
Front SAM control unit with fuse and relay module →
Diagnostic CAN →
HERMES control unit
The Supplemental Restraint System control unit transmits a readiness signal cyclically via the same route (e.g. every 500 ms). This enables the HERMES control unit to monitor communication with the supplemental restraint system control unit and correct operation 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 SOS 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 signal from the SOS button is sent over the following route: Overhead control panel electronics → HERMES control unit
| Electrical function diagram for manual or automatic emergency call function | PE82.95-P-2066-97HBC | ||
| Overview of system components, telematics | GF82.85-P-9999RR |