Subaru LEGACY 2002 Quick Reference Index page 306

Automatic Transmission
F: LINE-PRESSURE CONTROL DURING SHIFTING
The line pressure which engages shift clutches to create 1st to 4th speeds is controlled by the
TCM to meet varying operating conditions.
During gear shifting, the TCM decreases the line pressure to a level that matches the selected
gear in order to minimize shifting shock loads.
During gear shifting, the TCM controls the line pressure as follows:
! The TCM receives signals such as throttle position signal and accelerator pedal speed signal.
Based on these input signals, it issues a control signal to the line pressure duty solenoid.
! The pressure from the line pressure duty solenoid (line pressure duty pressure) is converted by
the pressure modifier valve into a modifier pressure, and the modifier pressure is applied to the
pressure regulator valve.
! The pressure regulator valve adjusts the oil-pump-generated line pressure according to the
modifier pressure to make the line pressure matched to the driving condition.
TRANSMISSION CONTROL MODULE (TCM)
AT-30
B3H0996B