Shift Patterns

UPSHIFTS

NOTE: Vehicles equipped with an OSS sensor will have new adaptive shift strategies. Whenever the vehicles battery has been disconnected for any type of service or repairs the strategy parameters that are stored in the Keep Alive Memory (KAM) will be lost. The strategy will start to learn once the battery is reconnected and the vehicle is driven. This is a normal condition and will go away once the PCM learns all the parameters from the driving conditions. There is no time frame set to this learning process. If this concern is present during down shifts or converter clutch apply, it is not the shift strategy and will require diagnosis.

The customer needs to be notified that they may experience slightly different upshifts either soft or firm and that this condition is normal and will eventually go away.

Transmission upshifting is controlled by the Powertrain Control Module (PCM). The PCM receives inputs from various engine or vehicle sensors and driver demands to control shift scheduling, shift feel and Torque Converter Clutch (TCC) operation.


DOWNSHIFTS
Under certain conditions the transmission will downshift automatically to a lower gear range (without moving the transmission range selector lever). There are three categories of automatic downshifts; Coastdown, Torque Demand and Forced or Kickdown shifts.


COASTDOWN
The coastdown downshift occurs when the vehicle is coasting down to a stop.


TORQUE DEMAND
The torque demand downshift occurs (automatically) during part throttle acceleration when the demand for torque is greater than the engine can provide at that gear ratio.


KICKDOWN
For maximum acceleration, the driver can force a downshift by pressing the accelerator pedal to the floor. A forced downshift into a lower gear is possible below calibrated speeds. Specifications for downshift speeds are subject to variations due to tire size, engine and transmission calibration requirements.