Shift Selection

Shift Selection
The TCM uses various driver selected modes and adaptive modes as below. Each mode introduces a different gear selection strategy, depending on driver requirements and driving conditions (vehicle status).

Driver selected modes:

- Normal mode:
- Activated by the sports 'S' switch on the J-Gate surround, the switch does not illuminate when normal mode is selected.
- Normal mode will remain active until the driver selects 'sports mode' or 'cruise control'. On the deactivation of 'cruise control', the system returns to the mode previously activated.
- Normal mode can be overridden by various adaptive modes.

- Sport mode:
- Activated by the sports 'S' switch on the J-Gate surround, the switch will illuminate when sport mode is selected.
- The sport mode strategy enables gearshift points to be extended to higher engine speeds, and downshifts at lower accelerator-pedal angles.
- Sport mode will remain active until the driver selects 'normal mode' or 'cruise control'. On the deactivation of 'cruise control', the system returns to the mode previously activated.
- Sport mode can be overridden by various adaptive modes.

- Cruise Control mode:
- When activated the TCM receives signals from the ECM via the CAN.
- The TCM implements a shift-map strategy to reduce gearshift activity and subsequently increase fuel economy.

Adaptive modes, these modes are selected automatically depending on driving conditions and vehicle status:

- Hot mode:
- A gear selection and torque converter lock-up strategy is implemented, to reduce heat generated in the transmission when any of the following become hot enough to reach a critical threshold value:
- Transmission fluid,
- Transmission casing,
- Engine oil,
- Engine coolant temperature.
- The hot mode strategy reduces generated heat by selecting higher gears and engaging the lock-up clutch at lower vehicle speeds.

NOTE: With hot mode implemented the driver may experience unexpected up-shifts when running at high vehicle speeds and loads.

- Traction Control mode:
- Under normal driving conditions an increase or decrease in wheel speed would be recognized by the TCM as the vehicle accelerating or decelerating and a gear would be selected in proportion to the speed of wheel rotation.
- In a situation where the vehicle is not accelerating in proportion to the wheel rotation speed, for example a slipping wheel. The TCM, in response to signals from the ABS module, will still command the transmission to select a higher-gear to help reduce wheel slip. The high gear will remain engaged until traction at the slipping wheel is regained.

- Gradient and Towing mode:
- The gradient and towing mode is activated when the TCM detects reduced vehicle acceleration at given throttle positions. This reduction in acceleration is recognized by the TCM as the vehicle either towing or ascending a gradient. Therefore, to provide the vehicle with maximum traction effort, a shift-map is used that extends the amount of time lower-gears are engaged, and subsequently delays the selection of higher gears.