Emergency Call System, Function - GF82.95-P-0004GWM

Model 463 (except 463.342) 

as of model year 2019 

with code EK1 (HERMES communications module LTE) 

Model 463 (except 463.342) 

as of model year 2019 

with code EM2 (Communications module (UMTS) for the use of Merced) 

Courtesy of MERCEDES-BENZ USA

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 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" 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 the driver hands-free system microphone, from the head unit
• Emergency call system antenna 1
• Emergency call system antenna 2
• 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 the fault 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 emergency call system function includes the following partial function:

• 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 
• Status indication via light-emitting diode 
• Status indication in instrument cluster 

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 and 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 transmits the display information to the head unit via the diagnostic CAN, electronic ignition lock control unit and user interface CAN.

The head unit transmits a switch-on request via the telematics CAN to the Audio/COMAND display, processes the visualization, and transmits the picture data to the Audio/COMAND display via the HSVL line.

Some text messages on the Audio/COMAND display can be confirmed using the Audio/COMAND control panel. The Audio/COMAND control panel transmits the signals to the HERMES control unit via the telematics CAN, head unit, user interface CAN, electronic ignition lock control unit and diagnostic CAN.

Status indication via light-emitting diode 

The SOS button LED is used to indicate the following statuses:

• Active service, light-emitting diode flashes
• Emergency call system self-diagnosis, light-emitting diodes light up for approx. 5 s
• Fault in emergency call system, LEDs permanently on
• Diagnosis

The HERMES control unit transmits the request to switch on the LED to the overhead control panel control unit via the diagnostic CAN, electronic ignition lock control unit and interior CAN. The overhead control panel control unit controls 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. The HERMES control unit continuously transmits the system status to the instrument cluster via the diagnostic CAN, electronic ignition lock control unit and user interface CAN.

Position finding 

The HERMES control unit receives the position finding signals from the head unit. The head unit transmits the position finding signals to the HERMES control unit via the user interface CAN, electronic ignition lock control unit and diagnostic CAN.

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 signals from the GPS antenna.

Additional function requirement for basic position finding 

• Terminal 15 ON

The electronic ignition lock control unit transmits circuit status "circuit 15" to the HERMES control unit via the diagnostic CAN.

Basic position finding 

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 transmits the wheel speed and yaw rate signals to the HERMES control unit via the chassis FlexRay, electronic ignition lock control unit and diagnostic CAN.

The steering column tube module control unit transmits the signals from the steering wheel angle sensor to the HERMES control unit via the chassis FlexRay, electronic ignition lock control unit and diagnostic CAN.

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 
• Voice connection between vehicle and Service Center 

Additional function requirements for triggering an automatic emergency call 

• Terminal 15 ON

The electronic ignition lock control unit transmits circuit status "circuit 15" to the HERMES control unit via the diagnostic CAN.

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 via the seat occupancy LIN as a digital crash signal from the supplemental restraint system control unit.

In addition (and redundantly), the Supplemental Restraint System control unit transmits the crash information - including the crash level - to the HERMES control unit via the user interface CAN, electronic ignition lock control unit and diagnostic CAN.

The supplemental restraint system control unit transmits a readiness signal cyclically (e.g. every 500 ms) via the same route as crash information. 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 overhead control panel control unit sends the status of the SOS button over the interior CAN, electronic ignition lock control unit and the diagnostic CAN to the HERMES control unit.

Voice connection between vehicle and Service Center 

Once the emergency call has been triggered, the HERMES control unit sets up a voice connection to the Mercedes-Benz Service Center over the emergency call system antenna 1 or the emergency call system antenna 2.

Emergency call system antenna 1 and emergency call system antenna 2 are used to set up the connection in order to form transmission and reception diversity.

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."

During an automatic emergency call, the Accept/End phone call switch on the multifunction steering wheel is temporarily disabled while the connection is being established to prevent the call being ended unintentionally.

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

For vehicles except code EU8 (Burmester 3D Surround Sound System), the HERMES control unit sends the signal for the mute function to the head unit.

For vehicles with code EU8 (Burmester 3D Surround Sound System), the HERMES control unit sends the signal for the mute function to the 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 driver hands-free system microphone, which is installed on the driver side of the roof interior trim, 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 from the driver hands-free system microphone via the head unit.

The HERMES control unit emits the incoming voice signals over the instrument cluster speaker.

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

• Head unit multifunction steering wheel button group 

  The steering wheel electronics read in the control signals from the volume control switch directly. The steering column tube module control unit reads them in over the steering-wheel CAN and sends them to the head unit over the suspension FlexRay, electronic ignition lock control unit and the diagnostics CAN to the HERMES control unit.

• Volume control button in the right lower control panel 

  The lower control panel at the right sends the operation signals over the LCP-LIN, Audio/COMAND control panel and the telematics CAN to the head unit. The head unit transmits the control signals to the HERMES control unit via the user interface CAN, electronic ignition lock control unit and diagnostic CAN.

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.

	Electrical function diagram for manual or automatic emergency call function		PE82.95-P-2066-97ZGE
	Overview of system components, telematics		GF82.85-P-9999GWM