System Operation
DESCRIPTIONShift scheduling, timing and feel (line pressure), as well as torque converter clutch (TCC) operation in the 4R44E are controlled electronically by the powertrain control module (PCM).
OPERATION
Input signals from various engine sensors give the PCM information about the engine's operating state. Other inputs are based on driver demands, such as the accelerator pedal position, which is monitored by the PCM using the throttle position (TP) sensor. Inputs are also supplied by the transmission itself. The turbine shaft speed (TSS) sensor and the transmission fluid temperature (TFT) sensor supply information to the PCM.
Using these input signals, the PCM can determine when the time and conditions are right for a shift or TCC application. The PCM controls six solenoids: three ON/OFF solenoids for upshifts and downshifts, one for pulse-width modulated control of the torque converter clutch, one for electronic line pressure control, and one ON/OFF solenoid for coast clutch application.