Function of Transmission Control

Transmission control function

TRANSMISSION 722.617 in MODEL 220.063
TRANSMISSION 722.618 in MODEL 220.065/165
TRANSMISSION 722.632 in MODEL 220.070/170
TRANSMISSION 722.633 in MODEL 220.075/175

Function
The transmission control is divided into the functions of electronic and hydraulic transmission control.

Whilst the electronic transmission control takes over the gear selection and adjustment of pressures to the torque to be transmitted, the performance actuation of the transmission takes place via the hydraulic components of the electrohydraulic control unit. The oil is supplied to the hydraulic components such as the hydrodynamic torque converter, shift components and hydraulic transmission control via an oil pump connected to the torque converter.

The electronic transmission control (ETC) enables an accurate adjustment of the pressures to the respective operating conditions and engine power during the shift phase which results in a significant improvement in shift quality.

It is possible to reach the engine speed limit in the individual gears at wide open throttle and kickdown. The selector lever positions can be changed in the forward gears while driving. but the electronic transmission control (ETC) prevents an unacceptably high engine speed by means of a downshift protection device.

Furthermore it has the advantage of flexible adaptation to the various vehicle and engine versions. The driver can choose between the two driving programs (normal driving program) and W (winter driving program), with different ratios also provided for reverse gear.

The electronic transmission is controlled as a function of the:
^ Vehicle speed
^ Position of selector lever
^ The pre-selected shift range
^ Program selection (W/S)
^ Transmission status
^ CAN signals

Also Refer To:
^ Transmission housing breather, function Function of Transmission Housing Breather
^ Oil pump, location/task/design/function Oil Pump
^ Oil level control, location/task/design/function Oil Level Control
^ Transmission control module, location/task/function Transmission Control Module
^ Selector lever positions, summary Survey of Selector Lever Positions
^ Emergency running mode, function Function of Emergency Running Mode
(To maintain a safe driving condition and prevent damage to the automatic transmission in the event of faults)
^ Operating pressure, function Function of Operating Pressure
^ Lubrication pressure, function Function of Lubricating Pressure
^ Shift pressure, function Function of Shift Pressure
^ Modulator pressure, function Function of Modulator Pressure
^ Regulating valve pressure, function Function of Regulating Valve Pressure
^ Shift valve pressure, function Function of Shift Valve Pressure
^ Control pressure, torque converter lock-up clutch, function Function of Torque Converter Lock-Up Clutch Control Pressure