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Key-P Function - GF27.10-P-3028ANG

Transmission 725.0 (except 725.017) in model 205 

Function requirements, general 

IMPORTANT The electronic ignition lock control unit (N73) transmits the status of circuit 15 via the chassis FlexRay (Flex E), the powertrain control unit (N127) and the drive train CAN (CAN C1) to the fully integrated transmission control unit (Y3/8n4).

The Electronic Stability Program control unit (N30/4) transmits the service brake status and the vehicle speed via the suspension FlexRay, powertrain control unit and drive CAN to the fully integrated transmission control unit.

IMPORTANT When a change is made from circuit 15 ON to circuit 15C ON or circuit 15C OFF, while the vehicle is driving rolling, the transmission control shifts automatically into transmission position "N". The vehicle can roll "freely".

Key-P, general 

Key-P comprises all the functions, which along with the parking brake, serve to secure the vehicle to prevent it from rolling away unintentionally.

Park pawl 

The park pawl only permits switching from transmission position "P" via the DIRECT SELECT lever (S16/13) with status circuit 15 On and the brake pedal pressed.

The steering column tube module control unit (N80) reads in the DIRECT SELECT lever switch position directly and sends it over the chassis FlexRay, powertrain control unit and the drive train CAN to the fully integrated transmission control unit. The fully integrated transmission control unit then controls engagement of the selected gear range.

The vehicle is secured mechanically by blocking the park pawl gear in the transmission.

If the driver opens the driver door after switching off the engine, the transmission control shifts into transmission position "P". The left front door control unit (N69/1) sends the status of the driver door (open or closed) over the interior CAN (CAN B), electronic ignition lock control unit, chassis FlexRay, powertrain control unit and the drive train CAN to the fully integrated transmission control unit. The fully integrated transmission control unit then controls engagement of transmission position "P".

"P" lock transmission position 

A gear range change from transmission position "P" cannot be executed if the following conditions are fulfilled:

The electronic ignition lock control unit sends the enable signal from the drive authorization system via the chassis FlexRay, powertrain control unit and powertrain CAN to the fully integrated transmission control unit and to the CDI control unit (N3/9) or ME-SFI control unit (N3/10).

  Electrical function schematic, Key-P   PE27.19-P-2058-97FBC
  Overview of system components for automatic transmission (AT)   GF27.10-P-9992ANG 
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