(Gearshift System, Basic Function - GF27.60-P-1002B)

Model all with transmission 725 

Overview 

This document contains information on:

• General 
• Function 
  • Shift operation 
  • Upshift and downshift 

General 

The gearshift system is responsible for changing between the various gears of the transmission.

Function 

Shift operation 

The fully integrated transmission controller unit converts the electrical signals coming from the fully integrated transmission control unit into hydraulic signals. Gear ranges "R", "N", "D1" to "D9", and "P" can be engaged by operating the DIRECT SELECT lever. Information on the engaged gear range "P", "R", "N", "D1" to "D9" is sent by the DIRECT SELECT lever to the fully integrated transmission control unit and the corresponding gear range is engaged.

The shift range for the engaged gear range "D1" to "D9" is displayed for the driver visually on the instrument cluster, for example. Although the shift range can be changed in the forward gears while driving, the fully integrated transmission control unit prevents a shift operation if the engine speeds are too high or too low.

Upshifts and downshifts 

In Sport ("S") transmission mode and Economy ("E") transmission mode, the driver can select the following functions by pressing the steering wheel gearshift buttons:

• Operating the steering wheel gearshift buttons in transmission mode "E" or "S" activates the short-term M mode. This allows the driver to change gear using the steering wheel gearshift buttons without having to select the M program beforehand. The previous "gear limitation/shift into optimum gear" function is discontinued by using the steering wheel gearshift buttons.
• In contrast to the continuous M program, the short-term M program is deactivated automatically after a specific period. This time interval starts again after every additional press of a button. The activity of the function is extended depending on the wide open throttle and lateral acceleration involved.
• In transmission mode "E", in comparison to transmission mode "S", a shorter shift range (shifting at low engine speed) and therefore a lower drive torque is available when starting off forwards and starting off in reverse. This allows for more economical and comfortable driving because the gears are not driven to the limit.
• In the Manual ("M") transmission mode, the individual gears "1" to "9" can be engaged directly via the steering wheel gearshift buttons.

It is only possible to shift into the reverse gear and neutral using the DIRECT SELECT lever. The park pawl (gear range "P") is activated by operating the park pawl on the DIRECT SELECT lever.