GEARSHIFTING With GEARTRONIC
When the gear selector is moved to the Geartronic position (+/-) the automatic transmission remains in hydraulic position D. When the gear selector is moved upwards (+) the gear selector module (GSM) transmits a signal to the transmission control module (TCM) to shift up. When the gear selector is moved downwards (-), a signal is transmitted to the transmission control module (TCM) to shift down. The driver information module (DIM) switches the symbol in the combined instrument panel from D to the current gear, for example 3, when the gear selector is in manual mode. A signal is also sent to the gear selector module (GSM) to light both the +/- LEDs and switches off the other LEDs. The transmission control module (TCM) determines if the shift can take place and the Driver information module (DIM) indicates the current gear. If shifting is permitted the solenoids are activated according to each specific gear pattern.
However, in certain situations the transmission control module (TCM) takes over responsibility for determining shifting. The follow 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. Speeds may vary due to engine version.
- Automatic downshifts take 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.
- Manual upshifting is required after automatic downshifting. Kickdown is not available in manual gear mode (+/-).
- Downshifting at Kickdown is permitted in manual gear mode (geartronic).
- Permitted RPM for manual downshifting correspond to the RPM for upshifting in kickdown.
- 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.
Miscellaneous
In manual gear position (+/-) a signal is generated on the position of the gear selector lever for the Gear Selector Module (GSM) in the following way: there is a Hall sensor 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 sensors' 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.