Start hybrid drive system, function - GF08.30-P-1003FLM

ENGINE 276.952 in MODEL 212.095 as of model year 2014 

ENGINE 651.924 in MODEL 212.098/298 as of model year 2014 

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

Information about the subfunction "ignition ON" from the point of view of the engine timing of the internal combustion engine are documented in the function description "ignition ON function".

Function requirements for starting the hybrid drive system - general points 

• Circuit 15 ON
• No Crash event occurred in the driving cycle
• Controlled Area Network (CAN) to all high voltage components are active and trouble-free
• High voltage security checked and released (no crash, no interlock error, no insulation error)

Starting a hybrid drive system - general points 

The activation function in the CDI control unit (N3/9) (for diesel engine) r the ME-SFI [ME] control unit (N3/10) (for gasoline engine) actuates precharging of the intermediate circuit and over the power electronics control unit (N129/1) and requests switching on of the contactor (A100s1) by the battery management system control unit (N82/2), assesses its status and frees up system readiness.

Starting the hybrid drive system, function sequence 

Upon switching on of circuit 15 the CDI control unit or the ME-SFI [ME] control unit makes the request for precharging of the intermediate circuit capacitor to the power electronics control unit via the hybrid CAN.

After precharging and appropriate feedback the CDI control unit or the ME-SFI [ME] control unit makes the request to switch on the contactor to the battery management system control unit via the hybrid CAN.

After successful switching on of the contactor, the battery management system control unit sets the status of the contactor on the hybrid CAN. In the case of failure of the status signal and message failure the CDI control unit or the 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 system to "system readiness".

The CDI control unit or the ME-SFI [ME] control unit transmits this status via the chassis CAN 1 (CAN E1), the front SAM control unit with fuse and relay module (N10/1) and the chassis CAN 2 (CAN E2) to the IC (A1), which displays the message "READY" (yellow) via the multifunction display (A1p13).

The vehicle is therefore ready to drive from the point of view of the hybrid system. Further subfunctions such as the automatic engine start or engine stop require a hybrid system with the message "READY" (green) and are dependent on further releases and system conditions.

Additional information concerning the required releases and system conditions for the automatic engine start or engine stop can be found in the following documents:

• Automatic engine stop, function 
• Automatic engine start, function