Shift Patterns

Shift Patterns

Upshifts

NOTE: This vehicle has been equipped with a special cold weather shift strategy. This was designed to maximize heater output. This new strategy operates under the following conditions: ambient air temperature at start-up is -4°C (25°F) or below and the engine coolant temperature at start-up is 38°C (100°F) or below. During this condition, the vehicle may experience slightly delayed shifts under light throttle. Medium and heavy throttle shifts will be normal. Once the engine coolant reaches 71°C (160°F) or above, normal shift scheduling will resume. If, during the diagnosing of a delayed shift concern, the concern goes away after the engine coolant reaches 71°C (160°F) or above, this is a normal operation of the special cold weather shift strategy. If this condition does not go away after the engine coolant reaches 71°C (160°F), refer to Diagnosis By Symptom. 4R100

NOTE: All gasoline vehicles will have new adaptive shift strategies. Whenever the vehicles battery has been disconnected for any type of service or repair, the strategy parameters that are stored in the keep alive memory (KAM) will be lost. The strategy will start to relearn once the battery is reconnected and the vehicle is driven. This is a temporary condition and will return to normal operating condition once the powertrain control module (PCM) relearns all the parameters from the driving operating conditions. There is no time frame set for this process. If this concern is present during downshifts or converter clutch apply, it is not the shift strategy and will require diagnosis.

The customer must be notified that they may experience slightly different upshifts (either soft or firm) and that this condition is temporary and will eventually return to normal operating condition.

Transmission upshifting is controlled by the 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, axle ratio and transmission calibration requirements.