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

TRANSMISSION 722.9 in MODEL 166 up to model year 2016

Function requirements for Key-P, general

Vehicle speed < 8 km/h

Key-P, general

The designation Key-P refers to the function by which the gear range P is engaged when the vehicle is stopped and the transmitter key (A8/1) is withdrawn.

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 subdivided into the following steps:

Park pawl function sequence
Function sequence for selector lever position "P" lock
Emergency-P function sequence (see document, Emergency-P Function )

Park pawl function sequence

The park pawl only permits shifting out of selector lever position "P" using 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. The "Circuit 15 ON" signal is sent by the electronic ignition lock control unit (N73) to chassis CAN 1 (CAN E1) and read in by the CDI control unit (N3/9) (with diesel engines) or ME-SFI control unit (N3/10) (with gasoline engines). The CDI control unit or the ME-SFI [ME] control unit routes the signal over the drive train CAN (CAN C) to the fully integrated transmission control unit (VGS) (Y3/8n4) and the intelligent servo module for DIRECT SELECT (A80). The vehicle is secured mechanically by blocking the park pawl gear in the transmission.

TRANSMISSION 722.9 in MODEL 166 up to model year 2016

with CODE 889 (KEYLESS-GO)

In vehicles with KEYLESS GO, the selector lever position "P" is engaged when the driver door is opened after the vehicle is parked. The left front door control unit (N69/1) routes the signal received from the left front door rotary tumbler switch (A85s1) as a status message over interior CAN (CAN B) to the KEYLESS-GO control unit (N69/5). The KEYLESS-GO control unit sends the status over the interior CAN and the chassis CAN 1 with the electronic ignition lock control unit interface to the CDI control unit or the ME-SFI [ME] control unit. This then forwards the request to engage gear range "P" over the drive train CAN to the intelligent servo module for DIRECT SELECT.

Function sequence for selector lever position "P" lock

The selector lever remains locked in position "P" if the following conditions are not met:

No power supplied to intelligent servo module for DIRECT SELECT
No enable signal from the drive authorization system (DAS 3)
Brake pedal not actuated
Transmitter key not in position "Circuit 15 ON"

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