Start Hybrid Drive System, Function - GF08.30-P-1003LFH

Engine 276 in model 222.057/157 

Engine 276 in model 222.163 

Engine 276 in model 222.173 

Engine 651.9 in model 222.004/104 

The subfunction "hybrid drive system start, function" is considered and described from the point of view of the hybrid drive system.

Information about the subfunction "Ignition ON" from the combustion engine management perspective is documented in the associated function.

Function requirements for starting the hybrid drive system - general points 

• Circuit 15 ON
• No crash signal in this ignition sequence
• Active and trouble-free CAN bus to all high-voltage components
• High voltage security checked and cleared (no crash event, no interlock circuit error, no insulation fault)

Starting a hybrid drive system - general points 

The activation function in the CDI control unit (N3/9) (for diesel engine) or ME-SFI control unit (N3/10) (for gasoline engine) actuates precharging of the high voltage intermediate circuit over the power electronics control unit (N129/1) and makes the request to battery management system control unit (N82/2) to switch on the contactor (A100s1), assesses its status and enables system readiness to operate.

Function sequence start for hybrid drive system 

When the hybrid drive system starts up, the CDI control unit or the ME-SFI [ME] control unit reads in the requests and signals from the following control units and sensors via the CAN network:

• Fully integrated transmission control unit (Y3/8n4) via the CAN network
  • Status of wet clutch (except model 222.173)
  • Status of engine separator clutch (model 222.173)
• Battery management system control unit via CAN network:
  • Voltage of high-voltage battery (A100g1)
  • Temperature of high-voltage battery
• Power electronics control unit
  • Status of the electrical machine (A79/1)
  • Hybrid drive system, status

When circuit 15 is switched on, the CDI or ME-SFI [ME] control unit sends a request for capacitor precharging (high voltage intermediate circuit) via the CAN network to the power electronics control unit. After precharging and appropriate feedback, the CDI or ME-SFI [ME] control unit sends a request to the battery management system control unit to switch on the contactor via the CAN network.

After successfully switching on the contactor, the battery management system control unit sends the status of the contactor to the CAN network. If no status signal and message is sent, the CDI or ME-SFI [ME] control unit sets the status of the contactor to a substitute value.

After successful activation of the high voltage on-board electrical system the CDI control unit or the ME-SFI [ME] control unit sets the status of the hybrid drive system to "system readiness".

The CDI or ME-SFI [ME] control unit transmits this status via the CAN network to the instrument cluster (A1), which shows the message "READY".

Further partial functions such as the automatic engine start or engine stop are dependent upon further release and system conditions.

Further information concerning the required releases and system conditions for the automatic engine start/engine stop is documented in the associated function:

	Electrical function schematic for starting the hybrid drive system		PE08.30-P-2056-97SEH
	Overview of system components, hybrid drive system		GF08.30-P-9999LFH