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Transmission Shift selection Shift Map Selection The transmission control system utilizes a number of driver selectable operating modes and also a number of adaptive/automatically selectable modes. Sport, Normal and Cruise Control mode are all driver selectable. Hot mode, traction control mode and trailer towing mode are all adaptive modes i.e. the transmission will automatically select this mode dependent upon the current driving conditions. Normal Mode Normal mode can be selected by activation of the transmission mode switch located on the J-Gate. Once activated this mode will remain engaged until the driver deselects the mode or engages the cruise control system. If the driver engages cruise control when Normal mode is active upon deactivation of the cruise system the transmission will automatically re-engage Normal mode. This mode can be over-ridden by a number of adaptive modes.
The mode switch is of the momentary type. Cruise Mode When the driver engages the cruise control system the TCM receives a CAN message transmitted by the Adaptive Cruise Control (ACC) or engine electronic controls which informs the TCM that cruise control is currently active. Upon receipt of this message the TCM selects a new transmission shift map. This map has been developed to reduce busy gearshift during cruise mode. It has also been developed to increase fuel economy. Hot Mode This is one of the adaptive modes the transmission can enter when conditions are correct. When the transmission fluid temperature, chip temp, engine oil temp or coolant temperature becomes hot enough to reach threshold values, the TCM will cause the transmission to enter Hot mode. This mode will automatically engage new shift and lock-up maps to reduce heat generated within the transmission. The shift map will enable the transmission to change to higher gears at lower vehicle speeds and the lock-up map will engage the lock-up clutch at lower vehicle speeds and in lower gears. The effect of this is that less heat will be generated within the transmission due to the effects of lock-up clutch slip and churning effects. There will be forced upshift strategy used in hot mode. To exit hot mode the selector lever must be moved or the brake pedal applied or the accelerator pedal applied 100%, during all of these methods of exiting from hot mode the fluid temperature must be lower than the threshold values. Traction Control Mode Traction Control Mode is an adaptive mode, which is automatically engaged when a traction event occurs. When driving on slippery surfaces (i.e.sand, ice) it is possible for the driven wheels to begin to spin. The TCM believes the vehicle speed is increasing and therefore it may begin to upshift. These upshifts reduce the torque at the wheel and so tend to reduce wheel slip. The downshift lines are forced downwards to prevent unwanted shifts. To reduce the effects of this, if a traction event occurs a signal is transmitted by the ABS module to the TCM over the CAN network, the TCM uses |