HERMES Control Unit, Component Description - GF82.85-P-0221RF
Model 205, 253
with code 362 (HERMES communications module LTE)
Model 205
up to model year 2019
with code 360 (HERMES UMTS)
Model 253 (except 253.99)
with code 360 (HERMES UMTS)
Figure shows model 205.0 up to model year 2019
Shown on model 253.9 (except 253.99) as of 01.06.2019
Location
Model 205.012/047/147/212/247
The HERMES control unit is located on a major assembly carrier in a recess in the rear area of the trunk under the paneling.
Model 205 up to model year 2019 (except for model 205.012/047/147/212/247)
The HERMES control unit is located in the front of the trunk under the paneling behind the rear bench seat.
Model 205 from model year 2019, model 253
The HERMES control unit is located in the center console behind the instrument panel cover near 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.
The HERMES control unit is responsible for the following tasks:
- Self-diagnosis for circuit 15 ON, secures operational readiness of emergency call system by checking the following facts:
- Reception of cyclic readiness signal from Supplemental Restraint System (SRS) control unit (N2/10)
- Connection for muting audio sources (mute function)
- Connection to hands-free system microphone (A67b1) (model 205 up to model year 2019, model 253 (except 253.99) up to model year 2020) or to driver hands-free system microphone (B25/20) (model 205 as of model year 2019, model 253 (except 253.99) as of model year 2020, model 253.99), via the head unit
- Connection to emergency call system antenna (A2/52)
- Connection to left telephone antenna (A2/102), right telephone antenna (A2/103) over the telephone antenna splitter (A2/109)
- Connection to GPS antenna (A2/23) (as of 01.06.2019)
- Reception of crash signals from Supplemental Restraint System control unit via the seat occupancy LIN (LIN E2) (trigger signal for the automatic emergency call)
- Reception of a request to initiate an automatic emergency call from the Mercedes-Benz Intelligent Drive control unit (N62/4) (the Active Emergency Stop Assist brakes the vehicle to a standstill) (model 205 as of model year 2019 with code 23P (Driving Assistance Package), model 253 (except 253.99) as of 01.06.2019 with code 23P (Driving Assistance Package))
- Set-up of voice or data connections to service provider
- For voice connections:
- Transmission of a mute signal to the audio sources
- Reception of signals from the hands-free system microphone (model 205 up to model year 2019, model 253 (except 253.99) up to 31.05.2019) or driver hands-free system microphone (model 205 as of model year 2019, model 253.99, model 253 (except 253.99) as of 01.06.2019) from the head unit (Input)
- Sending the audio signals to the center instrument panel speaker (H4/27)
- Reception of GPS signals (Global navigation system) for the position finding via the GPS antenna (as of 01.06.2019 or with code 520 (Audio 20 USB), code 522 (Audio 20 radio) and except code 355 (Pre-installation for navigation retrofit))
- Forwarding GPS signals to the head unit (as of 01.06.2019 with code 355 (Pre-installation for navigation retrofit), code 355 (Extended functions MBUX), code 365 (Hard disk navigation) or code 531 (COMAND APS))
- Receiving position data from the head unit for position finding via the diagnostics CAN (CAN D) (with code 355 (Pre-installation for navigation retrofit), with code 355 (Extended functions MBUX), with code 365 (Hard disk navigation) or with code 531 (COMAND APS))
- Forwarding real-time traffic data from the service provider to the head unit (with code 367 (Live Traffic Information)):
- Via a direct line (with code 360 (HERMES UMTS))
- Via WLAN (with code 362 (HERMES LTE))
- Communication of Internet signals to the head unit via WLAN or Bluetooth®
- CAN communication via the hybrid CAN (CAN L) (Plug-in hybrid and model 253.99) and diagnostics CAN
The HERMES control unit receives and sends, among other things, the following signals via the hybrid CAN:
- Vehicle data on charge level, expected charging time and range, from the powertrain control unit (N127)
- Vehicle data on pre-entry climate control through the climate control, control unit (N22/1), from the powertrain control unit
- Remote data requests and operation signals, to the powertrain control unit
The HERMES control unit receives the following signals, among others, via the diagnostic CAN:
- Readiness signal from Supplemental Restraint System control unit
- Crash information from Supplemental Restraint System control unit (redundant) (automatic emergency call)
- SOS button status (N70s11) from overhead control panel control unit (N70) (except model 205.4) (manual emergency call)
- Breakdown assistance button status (N70s12) and MB info status button (N70s13) (model 205 up to model year 2019, model 253 (except 253.99) up to model year 2020) or Mercedes me connect button (N70s16) (model 205 as of model year 2019, model 253 (except 253.99) as of model year 2020, model 253.99) from overhead control panel control unit (except model 205.4)
- Status of the emergency call system button group (S93/3) (model 205.4)
- Control signals from controls on the multifunction steering wheel (e.g. volume control, mute, connect/disconnect)
- Steering wheel angle from steering column tube module control unit (N80) (position finding)
- Wheel speed signals, yaw rate signals from the Electronic Stability Program control unit (N30/4) (position finding)
- Positioning data from the head unit (position finding) (with code 355 (Pre-installation for navigation retrofit), with code 355 (Extended functions MBUX), with code 365 (Hard disk navigation) or with code 531 (COMAND APS))
- Model 205.012/047/147/212/247, 253.354/954/99:
The HERMES control unit transmits the following signals, among others, via the diagnostic CAN:
- Request for status via "Display emergency call system" button group to the front SAM control unit (model 205.4)
- Status request via SOS button (manual emergency call), breakdown assistance button, and MB info button (model 205 up to model year 2019, model 253 (except 253.99) up to model year 2020), or Mercedes me connect button (model 205 as of model year 2019, model 253 (except 253.99) as of model year 2020, model 253.99) to the front SAM control unit (except model 205.4)
- Check signal for the emergency call system self-test
- Map data and miscellaneous data transmitted by the Service Center ("Remote Information Feed") to the head unit (with code 494 (USA version))
- Status signals to the instrument cluster (A1)
- Display messages for showing on the Audio/COMAND display (A40/8) to the head unit
- Operation signals to the powertrain control unit (with code ME05 (HYBRID DRIVE 80KW VARIANT (INCLUDING PLUG-IN)) or code ME06 (hybrid drive 60 KW variant (including plug-in)) or model 253.99)
HERMES stands for: Hardware for Enhanced Remote, Mobility & Emergency Services.
The HERMES control unit calculates the vehicle position and if necessary, it sends a message to the service center.
The HERMES control unit is prepared to send and receive for a period of 30 days. As soon as an SMS is received, the HERMES control unit is also activated (wakeup). After 30 days, the emergency call system enters sleep mode.
Structure
The HERMES control unit contains the following components:
- Internet-compatible communication module with Bluetooth® interface and radio interface for WLAN
- Position finding module
- 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 data transferred to the vehicle
| Wiring diagram of HERMES control unit | Model 205 up to model year 2019, model 253 (except for 253.99) up to model year 2020 | PE82.85-P-2107-97FBA | |
| Model 205 as of model year 2019 with code 362 (HERMES communications module LTE) | PE82.85-P-2107-97FBB | ||
| Model 253.99 | PE82.85-P-2107-97FCA | ||
| Model 253 (except 253.99) as of model year 2020 with code 360 (HERMES UMTS) | PE82.85-P-2107-97FCB |