Principle of Operation

Principle of Operation
Transmission Control





The GA6HP19Z / GA6HP26Z gearbox is controlled by the mechatronics module that is made up of a combination of the valve body and electronic transmission control unit (EGS). The drive range switch (for drive ranges P. R. N and D) is located in the mechatronics module. It is operated by the selector lever in connection with a bowden cable assembly.
The electrical signals of the drive range switch are evaluated in the mechatronics module and used for the purpose of controlling the solenoid valves and pressure regulator. The hydraulic selector (shaft in the valve body) is shifted (P. R. N. D) and the parking lock is operated by the bowden cable assembly.
The sequential gearshift takes place electrically by a switch on the selector lever mechanism (see automatic and Steptronic mode).





The electronic transmission control unit is an integral part of the mechatronics module (installed in the oil sump of the gearbox). The electronic inputs are evaluated in the control unit and electronic output signals control the actuators. The control unit is integrated in the E60 PTCAN system.





The data that the EGS requires for shifting gears, such as injection timing, engine speed, throttle valve angle, engine temperature and engine intervention, are transmitted on the PTCAN bus. The solenoid valves and the pressure actuator are activated directly by the Mechatronics Module. Messages that are sent via the PTCAN bus to the EGS control unit and from the EGS control unit are:
Hall sensors detect the turbine and output speed of the gearbox. The signal from the drive range switch is also routed via 4 Hall sensors to the mechatronics module. Two temperature sensors are used for acquiring the transmission fluid temperature.

Automatic and Steptronic Mode





The shift gate pattern is located in the selector lever panel. The engaged drive range is highlighted on the shift gate pattern. The background highlighting is activated by the sliding contact on the selector lever.

Selecting Lever Positions in Automatic Mode AT
The gears are shifted automatically as part of the EGS program in the automatic shift gate (1) selector lever position D. The display in the instrument cluster shows D. The signal for the display in the instrument cluster is provided by the Mechatronics Module.

Selecting Lever Positions in Steptronic Mode
The S-Program is selected by shifting the selector lever out of position D into the manual shift gate (2). The display in the instrument cluster changes to D S. Steptronic mode is activated by tapping the selector lever forward or backward and the transmission is shifted one gear up or down.
The display in the instrument cluster changes to M1 M6. In Steptronic mode, the respective gear is maintained up to just before reaching the governed engine cutoff speed. An upshift then takes place automatically. Automatic downshifts are performed at kickdown and speed dependent to 3rd and 2nd gear.
If a chosen gearshift is not permitted because of the engine and vehicle speed, the display in the instrument cluster initially changes to the chosen gear and then to the actual gear. The chosen gear is not shifted before reaching the permissible engine speed or vehicle speed. This function prevents engine overreving.
The required gear is stored by tapping the selector lever several times and subsequently holding the position. The transmission shifts in succession up to the gear indicated in the instrument cluster. The selector lever must be held in position until the required gear is reached.
Plausibility Check Since the selector lever can be moved into the manual shift gate only from position D, detection of the "manual shift gate" signal is permitted only together with the "position D" signal. Detection of the + or signals for upshift or downshift is permitted in the manual shift gate only. If a fault occurs, a corresponding fault code is entered in the fault code memory and the S-Program as well as Steptronic mode are deactivated.

Selector Lever Display in the Instrument Cluster


The engaged drive range is displayed in the instrument cluster (same as on the E46/E39) and is controlled by the Mechatronics Module.

Shift Lock
The shift lock prevents moving the selector lever from the drive ranges "P and N" when the service brake (pedal) is not operated. This function is accomplished by an electromagnetic lock on the selector lever.

Interlock
A cable assembly is fitted between the selector lever and ignition lock (in the steering column). It ensures the ignition key can be removed only when the selector lever is in position "P" (same as on the (E38) 740i, 750i.