Gearshifting With Geartronic
When the gear selector is moved to Geartronic mode (MAN), the automatic transmission is still hydraulically in D . If the gear selector is moved up (+), the gear selector module sends a signal to the transmission control module (TCM) to upshift. If the gear selector is moved down (-), a signal is sent to the transmission control module (TCM) to downshift. When the gear selector is in MAN mode, the driver information module (DIM) will change its symbol from D to the currently engaged gear, such as 3. A signal is also sent to the gear selector module (GSM) to light the LED for MAN and deactivate other LEDs. The transmission control module (TCM) determines whether the shift is possible. The driver information module (DIM) indicates the current gear. If shifting is permitted, the various solenoids are activated in the pattern specific to the relevant gear.
In certain situations however the Transmission Control Module (TCM) takes over the gearshift decisions. Amongst other things, the following applies:
- When stationary, only gears 1, 2 and 3 can be selected. Gear 4 can be selected at speeds above 40 km/h and gear 5 at speeds above 55 km/h, and gear 6 at speeds above 70 km/h.
- Automatic downshifting takes place on all gears when below a certain speed. Example: Gear 2 is selected. Automatic downshifting then takes place from gear 2 to gear 1 at 2 km/h if the speed before this exceeded 25 km/h. Otherwise gear 2 remains engaged. However, situations can arise where gear 3 remains engaged despite the vehicle stopping.
- A manual upshift is required after an automatic downshift. Kickdown is not available in Geartronic mode.
- Permitted speeds for the manual downshifts equate to those for kickdown upshifts, i.e. an engine speed of approx. 6000 RPM.
- If transmission temperature becomes too high then the Transmission Control Module (TCM) takes over the gearshift decisions. The purpose of this is to engage a gear where lock-up is possible at the current speed.
- Lock-up is possible for gears 2, 3, 4, 5 and 6.
Other
- In MAN mode, a signal on gear selector lever position is generated for the gear selector module (GSM) as follows: a Hall sensor is fitted on the printed circuit board for the gear selector module (GSM) for each one of the three gear selector lever positions. A permanent magnet on the gear selector lever acts on the sensor output signals to the control module. The control module can read off the position of the gear selector lever by means of the differences in signal character.