Subaru XT 1988 Service Manual page 564

3-2
AUTOMATIC TRANSMISSION AND DIFFERENTIAL
(3) 3-2
Timing Control
When shifting from 3rd to 2nd, the high clutch is disengaged.
At the same time, oil pressure (which releases the brake band)
is also released from the servo piston 3rd release chamber
(3R).
Se rvo piston 3rd
release chamber
oi I pressu re .---p
At this point, the servo piston moves to release oil pressure
from the 3rd release chamber (3R) and apply oil pressure to
the 2nd apply chamber. This causes the brake band to be
applied. In other words, high clutch "release" and brake band
"application" are properly timed by electronic control. Th is
eliminates engine rev·up under no load or hesitation.
High clutch
apply pressu re
Timing control
solenoid (shift
solenoid 3)
Fig. 70
• When the 3-2 timing valve conducts, oil pressure applied
to the 3rd release chamber is quickly released through
passage
@.
50
AfT
control
unit
L3-931
• When the 3-2 timing valve does not conduct, oil pressure
appl ied to the 3rd release chamber is slowly released
through passage
@
(provided with an orifice).