Electronic transmission control (EGS)

The electronic transmission control (EGS) processes signals from gearbox, engine and vehicle. The desired state of the gearbox is calculated in conjunction with stored data and from these signals, such as:

• Gear selection
• Converter lockup clutch strategy
• Specified setpoint value for activation of brakes and clutches

To implement the specified setpoint values, solenoid valves and pressure regulators are actuated using the power output stages and current regulator circuits. This controls the hydraulics of the automatic transmission.

The following sensors are in the gearbox:

• Turbine speed sensor
• Output speed sensor
• Position sensor to detect the parking lock position
• Gearbox oil temperature sensor
• Substrate temperature sensors

The processor of the electronic transmission control (EGS) has an internal memory of 2048 kilobyte. The basic gearbox program occupies approx. 1536 kilobyte. The approx. 512 kilobyte remaining include the vehicle-specific application data. You can program the electronic transmission control (EGS). The main part of the programming process was performed by the Digital Engine Electronics (DME) programming. Adapting the functionality of the electronic transmission control (EGS) was implemented.

Adaptations are performed automatically during the journey. After having performed repair work on the 8-speed automatic gearbox or replacing the 8-speed automatic gearbox, adaptations must be reset using the diagnosis system. Subsequently go for a test drive and engage all gears.

The valve body is located inside the mechatronics module. It includes valves and channels for hydraulic control. The valve body is divided into a lower section (valve body) and an upper section of the valve plate. They are separated by an intermediate plate. The following components are in the lower section:

• 14 hydraulic valves
• 7 electronic pressure control valves
• 1 solenoid valve
• 1 parking lock magnet to lock the parking lock

There are seven additional hydraulic valves in the upper section as well as inserts such as balls, screen filters and plate valves. The electronics module including the electronic transmission control (EGS) is fitted in the top valve body. The hydraulic lines on the upper section are the connection to the channels and connectors of the gearbox housing.

Fig 1: Identifying Torque Converter Components

Courtesy of BMW OF NORTH AMERICA, INC.