HERMES Control Unit, Component Description - GF82.85-P-0221FH

Model 238 

Up To Model Year 2021 

With Code 360 (HERMES UMTS) 

Model 238 

Up To Model Year 2021 

With Code 362 (HERMES communications module LTE) 

Shown On Model 238.3 

Location 

The HERMES control unit is located in the rear center instrument panel behind the upper control panel control unit (N72/1) and above the head unit (A26/17).

Tasks 

The HERMES control unit controls communication between the vehicle and the service provider or user, and therefore make it possible to use numerous vehicle-related services. In order to obtain transmission and reception diversity, 2 antenna connections are used for communications in vehicles with code 362 (HERMES LTE).

"HERMES" stands for: "Hardware for Enhanced Remote, Mobility & Emergency Services".

The HERMES control unit has the following individual tasks:

• Reception of power supply via circuit 30t and circuit 31 (input)
• With code 351 (Emergency call system (HERMES)): Self-test, ensuring that the emergency call system is functional by checking the following:
  • Reception of cyclic readiness signal ("sign of life") from the Supplemental Restraint System control unit (N2/10) via the seat occupancy LIN (LIN E2)
  • Connection for muting audio sources (mute function)
  • Connection to driver hands-free system microphone (B25/20), through head unit
  • Connection to the emergency call system antenna 1 (A2/140)
  • Connection to emergency call system antenna 2 (A2/141) (model 238.3 with code 362 (HERMES LTE)) or to the telephone antenna splitter (A2/109) (model 238.4 with code 362 (HERMES LTE))
• Reception of crash signals from the Supplemental Restraint System control unit via the seat occupancy LIN (and redundantly via the diagnostic CAN (CAN D))
• As of 01.06.2019 or with code 520 (Audio 20 USB) or with code 522 (Audio 20 radio) and except code 355 (Pre-installation for navigation retrofit): Reception of GPS (global navigation system) signals for position finding via the GPS antenna (A2/23) (input)
• Establishing voice connections or data links the service provider via emergency call system antenna 1, emergency call system antenna 2 (model 238.3 with code 362 (HERMES LTE)) or the telephone antenna splitter (model 238.4 with code 362 (HERMES LTE)) (input and output)
• As of 01.06.2019: Transmission of GPS signals to the head unit (with code 355 (Pre-installation for navigation retrofit) or with code 531 (COMAND APS)) (output)
• With voice connections: Transmitting of the mute function signal to following components (output):
  • Sound system amplifier control unit (N40/3) (with code 810 (Sound system))
  • Advanced sound system amplifier control unit (N40/7) (with CODE 811 (Advanced sound system))
  • Head unit (model 238 (except 238.361/461) except code 810 (Sound system) and except code 811 (Advanced Sound System))
  • Midline sound system amplifier control unit (N40/2) (model 238.361/461 except code 810 (Sound system) and except code 811 (Advanced Sound System))
• For voice connections: Reception of signals from driver hands-free system microphone via head unit (input)
• With voice connections: Transmitting of the audio signals to the following components (output):
  • Center instrument panel midrange speaker (H4/78) (with code 811 (Advanced sound system))
  • Center instrument panel speaker (H4/27) (except code 811 (Advanced sound system))
• With code 367 (Live Traffic Information) and code 522 (Audio 20 radio): Forwarding of real-time traffic data via multimedia connection unit (A90/5) to head unit and reception of position data from head unit (USB (universal serial bus) connection, input and output)
• With code 367 (Live Traffic Information) and except code 522 (Audio 20 radio): Forwarding of real-time traffic data via integrated radio interface and WLAN antenna (A2/83) to head unit and reception of position data from head unit (radio interface)
• With code 506 (Audio 20 radio NTG 5.5) or code 531 (COMAND APS): Communication of Internet signals via the radio interface and the W-LAN antenna to the head unit (radio interface)
• With code 494 (USA version) and with code 522 (Audio 20 radio): Communication of Internet signals via interface for Bluetooth® and the Bluetooth® antenna (A2/91) to the head unit (interface for Bluetooth®)
• CAN communication via the diagnostic CAN with the electronic ignition lock control unit (N73) (CAN interface)

The HERMES control unit can receive, e.g. the following CAN signals over the electronic ignition lock control unit:

• Status of "Circuit 15R" from the electronic ignition lock control unit (trigger signal for the self-test of the emergency call system)
• Crash signal from the Supplemental Restraint System control unit (redundant) (automatic emergency call)
• SOS button (N70s11) (model 238.3) or SOS button (S93/3s2) (model 238.4) control signal from overhead control panel control unit (N70) (Manual emergency call)
• Operation signal of the Mercedes me connect button (N70s16) (model 238.3 as of 01.06.2018) or the Mercedes me connect button (S93/3s6) (model 238.4 as of 01.06.2018) from the overhead control panel control unit (telematics services)
• Operation signal of the breakdown assistance button (N70s12) and the MB-Info button (N70s13) (model 238.3 up to 31.05.2018) or the breakdown assistance button (S93/3s3) and the MB-Info button (S93/3s1) (model 238.4 up to 31.05.2018) from the overhead control panel control unit (telematics services)
• Operation signals of the instrument cluster multifunction steering wheel button group (S163/1) (up to 31.05.2018) and the head unit multifunction steering wheel button group (S163/2) from the steering column tube module control unit (N80) (volume setting, disconnect connection)
• Position data from the head unit (position finding)
• Wheel speed signals, yaw rate signals from the Electronic Stability Program control unit (N30/4) (position finding)
• Signals of the steering wheel angle sensor (N49) from the steering column tube module (MRM) control unit (position finding)

The HERMES control unit can transmit the following CAN signals, for example:

• Actuation of light-emitting diodes in the following buttons via the electronic ignition lock control unit to the overhead control panel control unit (status indication):
  • SOS button (N70s11) (model 238.3) or SOS button (S93/3s2) (model 238.4)
  • Mercedes me connect button (N70s16) (model 238.3 as of 01.06.2018) or Mercedes me connect button (S93/3s6) (model 238.4 as of 01.06.2018)
  • Breakdown assistance button (N70s12) (model 238.3 up to 31.05.2018) or breakdown assistance button (S93/3s3) (model 238.4 up to 31.05.2018)
  • MB-Info button (N70s13) (model 238.3 up to 31.05.2018) or MB-Info button (S93/3s1) (model 238.4 up to 31.05.2018)
• Map data and miscellaneous data transmitted from the Service Center ("Remote Information Feed") via the electronic ignition lock control unit to the head unit (telematics services)
• Status signals to the instrument cluster (A1) via the electronic ignition lock control unit
• Display messages for showing on Audio/COMAND display (A40/8), over the electronic ignition lock control unit and the head unit
• Request of data or actions for telematics services via the electronic ignition lock control unit to the control units involved

The HERMES control unit is ready for reception and transmission for 30 days: As soon as an SMS is received, the HERMES control unit is also activated (wake-up); after 30 days, the emergency call system goes into "sleep mode". Following circuit 15 ON a self-test is performed.

Structure 

• Integrated Internet-compatible communications module with Bluetooth® interface and radio interface for wireless local area network (WLAN)
• Integrated locating module
• Integrated GPS receiver for position finding (date, time, history and last-known location) for the listed vehicle-related services
• Memory for vehicle-specific data
• Buffer for map and other data that is transmitted to the vehicle

Wiring diagram of HERMES control unit

PE82.85-P-2107-97DCA