Emergency-P function - GF27.10-P-3029AHL

TRANSMISSION 722.9 (except 722.930/931) in MODEL 212 

Function requirements for Emergency-P, general 

• Emergency motor supply voltage

Emergency-P, general 

In emergencies, if for example undervoltage prevails in the on-board electrical system or the communication with the intelligent servo module for DIRECT SELECT (A80) is faulty, the emergency motor in the intelligent servo module for DIRECT SELECT is powered by the additional battery (G1/7) via the electronic ignition lock control unit (N73) and thereby triggers the emergency P function.

Function sequence for emergency-P 

The function sequence is described in the following steps:

• Function sequence for start position 
• Function sequence for intermediate position 
• Function sequence for end position 
• Function sequence for cancellation 

Function sequence for start position 

Fig 1: Function Sequence For Start Position

Courtesy of MERCEDES-BENZ USA

The additional battery supplies the emergency motor with voltage via the electronic ignition lock control unit in an emergency, e.g. in the event of undervoltage in the on-board electrical system.

This causes the eccentric shaft to turn.

Function sequence for intermediate position 

Fig 2: Function Sequence For Intermediate Position

Courtesy of MERCEDES-BENZ USA

The rotating eccentric shaft presses down onto the release studs of the left carriage half.

This in turn causes the mechanical connection between the left carriage half and right carriage half to be broken.

Function sequence for end position 

Fig 3: Function Sequence For End Position

Courtesy of MERCEDES-BENZ USA

The pre-compressed coil spring pushes the two slider halves apart. The right carriage half slides along the threaded spindle to the right and pushes the range selector lever to position "P". The eccentric shaft rotates until the emergency motor is no longer actuated. The actual position of the eccentric shaft is detected by the eccentric shaft position sensor and passed on to the electronics of the intelligent servo module for DIRECT SELECT.

Function sequence for cancellation 

The emergency P-function is automatically overridden, if the emergency case, which, e.g. is caused by undervoltage in the on-board electrical system, is no longer given. The main motor drives the worm shaft by way of the drive belts. The left carriage half runs on to the right carriage half, the coil spring is pre-compressed again and the mechanical connection made again.

The Emergency-P function cannot be overridden manually.