Subaru Impreza 2003, Service Manual

Page: 1569 / 3610

4AT-37
AUTOMATIC TRANSMISSION
LINE PRESSURE TEST
7. Line Pressure Test
A: MEASUREMENT
NOTE:
If the clutch or the brake shows a sign of slippage or
shifting sensation is not correct, the line pressure
should be checked.
• Excessive shocks during upshifting or shifting
takes place at a higher point than under normal cir-
cumstances, may be due to the line pressure being
too high.
• Slippage or inability to operate the vehicle may,
in most cases, be due to loss of oil pressure for the
operation of the clutch, brake or control valve.
1) Line pressure measurement (under no load)
(1) Before measuring the line pressure, jack-up
all wheels.
(2) Maintain the temperature of ATF at approx.
70 — 80
°
C (158 — 176
°
F) during measurement.
(ATF will reach the above temperature after
idling the engine for approx. 30 minutes with se-
lect lever in “N” or “P”.)
2) Line pressure measurement (under heavy load)
(1) Before measuring the line pressure, apply
both foot and parking brakes with all wheels
chocked (Same as for “stall” test conditions).
(2) Measure the line pressure when select lever
is in “R”, “2” with engine under stall conditions.
(3) Measure the line pressure within 5 seconds
after shifting the select lever to each position. (If
line pressure needs to be measured again, allow
the engine to idle, and then stop it to cool down
for at least one minute.)
(4) Maintain the temperature of ATF at approx.
70 — 80
°
C (158 — 176
°
F) during measurement
(ATF will reach the above temperature after
idling the engine for approx. 30 minutes with the
select lever in “N” or “P”.)
3) Temporarily attach the ST to a suitable place in
the driver's compartment, remove the blind plug lo-
cated in front of the toe board and pass the hose of
the ST to engine compartment.
ST 498575400 OIL PRESSURE GAUGE
ASSY
4) Remove the test plug and install the ST instead.
ST
498897200 OIL PRESSURE GAUGE
ADAPTER
5) Connect the ST1 with ST2.
ST1
498897200 OIL PRESSURE GAUGE
ADAPTER
ST2 498575400 OIL PRESSURE GAUGE
ASSY
6) Check for duty ratio changes by opening and
closing the throttle valve using SUBARU Select
Monitor.
(A) Pressure gauge hose
(B) Hole in toe board (blank cap hole)
(C) Brake pedal
(A) Test plug
Standard line pressure
Range
position
Line pres-
sure duty
ratio (%)
Throttle
position
Line pressure
kPa (kg/cm
2
, psi)
2 5 Full open
1,128 — 1,304
(11.5 — 13.3,
164 — 189)
R 5 Full open
1,520 — 1,716
(15.5 — 17.5,
220 — 249)
D 95 Full closed
304 — 412
(3.1 — 4.2, 44 — 60)
AT-00019
( A )
( B )
( C )
AT-00675
(A)