Automatic Transmission/Transaxle: Description and Operation

Control of the automatic transmission

The control of the automatic transmission consists essentially of the transmission control module and the hydraulic selector unit.

Transmission Control

The transmission control is divided mainly into the following components:

Transmission control module:

Power supply for solenoid valves and electronic pressure control valves

Evaluation of the sensor system

Transmission sensor system:

Sensor for the transmission input speed

Sensor for the transmission output speed

Transmission oil temperature sensor

Gearbox actuator system:

Solenoid valves

Electronic pressure actuators

Gearbox connector for connection to the gearbox and vehicle wiring harness

Transmission control module
On this transmission, the transmission control module is fitted as a separate control module. Firstly, it evaluates the sensors electronically and directly activates the actuators of the hydraulic selector unit. A temperature sensor additionally monitors the gearbox oil temperature.

Hydraulic selector unit
The hydraulic selector unit in the gearbox is similar to the hydraulic modules commonly used until now in gearboxes. It contains the hydraulic actuator system (solenoid valves, electronic pressure actuators) of the gearbox.