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

TRANSMISSION 722.9 (except 722.930) in MODEL 205 

Key-P function requirements, general 

• Status "Circuit 15 ON"
• Brake pedal operated
• Vehicle speed < 8 km/h

Key-P, general 

The designation "Key-P" comprises all the functions, which in addition to the parking brake, help to secure the vehicle to prevent it from rolling away unintentionally.

If the ignition key is turned to position "0" (circuit 15 C) and removed while the vehicle is driving or rolling, the transmission is automatically shifted to gear range "N". As a result, the vehicle can roll "freely".

Key-P function sequence 

The function sequence is described in the following steps:

• Park pawl function sequence 
• Function sequence for locking in gear range "P" 

The Emergency-P function is described in a separate document.

Park pawl function sequence 

The park pawl only permits shifting out of gear range "P" by the DIRECT SELECT lever (S16/13) if the transmitter key (A8/1) is turned to position "circuit 15 ON" and the brake pedal is operated.

In order to ensure that, after parking the vehicle, a shift is made to gear range "P", the transmitter key can only be removed in this position from the electronic ignition lock control unit (N73).

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

With CODE 889 (Keyless-Go)

For vehicles with CODE 889 (Keyless-Go), a shift is made to selector lever position "P" when the driver opens the driver door after parking the vehicle.

The left front door control unit (N69/1) sends the status of the left front door rotary tumbler switch (A85s1) via interior CAN (CAN B) to the electronic ignition lock control unit and onward via the chassis FlexRay (Flex E) to the powertrain control unit (N127). The powertrain control unit feeds the information further via the engine CAN (CAN C) to the CDI control unit (N3/9) or the ME control unit (N3/10) and to the fully integrated transmission control unit (Y3/8n4).

Function sequence for locking in gear range "P" 

A gear change from the "P" position cannot be executed if the following conditions are not met:

• No power supply from intelligent servo module for DIRECT SELECT (A80)
• No enable from the drive authorization system stage 4 (FBS4)
• Brake pedal not actuated
• Transmitter key not in position "Circuit 15 ON"

	Electrical function schematic, Key-P		PE27.19-P-2058-97FBA
	Emergency-P function		GF27.10-P-3029AHE
	Overview of system components for automatic transmission (AT)		GF27.10-P-9992AHE