Ignition switch lock, function - GF27.10-P-3003NT

TRANSMISSION 722.9 in MODEL 171.4, 203 up to Model Year 8 

TRANSMISSION 722.9 in MODEL 209, 211, 219 

Fig 1: Ignition Switch Lock Function Chart - Selector Lever Position P

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Selector lever position "P" 

Fig 2: Ignition Switch Lock Function Chart - Selector Lever Position D, R, N

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Selector lever position "D", "R", "N" 

Ignition switch lock, function 

The ignition lock mechanism connects the electronic selector lever module control unit (N15/5) with the EIS control unit (N73). It prevents the transmitter key (A8/1) from being withdrawn when the selector lever is not at position "P". When the parking lock is not engaged (selector lever position "D", "R", "N"), the locking valve (60) locks the locking cam (61). The compression spring (62) only pulls the locking valve (60) away from the locking cam (61) in selector lever position "P". The transmitter key (A8/1) can now be turned to position "0" and removed from the ignition.

In addition to the mechanical connection to the EIS control unit (N73), there is an electrical connection to the electric steering lock control unit (N26/5). In selector lever position "P", a load switch establishes the connection from the EIS control unit (N73) to the electric steering lock control unit (N26/5). The contact is closed in selector lever position "P", and forcibly open in all other selector lever positions in order to prevent activation of the electronic steering lock while driving.