GF27.60-P-2002SK Function of Transmission Control

GF27.60-P-2002SK Function of transmission control
- Transmission 722.6
- except CODE (428) Steering wheel shift buttons


Transmission control is divided into the functions of electronic transmission control (ETC) and hydraulic transmission control. Whilst the electronic transmission control (ETC) takes over gear selection and the adaptation of pressures to the torque to be transmitted, the power supply control of the automatic transmission takes place via the hydraulic elements of the electro hydraulic control unit. The oil supply to the hydraulic elements, such as the hydrodynamic torque converter, the shift elements and the hydraulic transmission control, is provided by way of an oil pump connected with the torque converter.

The electronic transmission control (ETC) makes possible a precise adaptation of pressures to the respective operating conditions and to the engine output during the gearshift phase, resulting in a significant improvement in shift quality. The engine speed limit can be reached in the individual gears at full throttle and kick down.

The shift range can be changed in the forwards gears while driving, however the ETC prevents an unacceptably high engine speed by means of a downshift lockout device

Furthermore ETC offers the advantage of a flexible adaptation to various vehicle and engine versions. The driver can choose between the two transmission modes "S" (sport program) and "C" (comfort program). These also provide different gear ratios for reverse gear.

The ETC [EGS] control unit (N15/3) monitors and shifts depending on:
^ The vehicle speed
^ The position of the selector lever
^ Accelerator pedal position
^ Program selection ("C/S")
^ The state of the transmission
^ Controller Area Network (CAN) signals