Line Pressure Test - Subaru Impreza 2004 Service Manual

AUTOMATIC TRANSMISSION

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" (HOLD switch ON) with engine un-
der 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.
Line Pressure Test
ST 498575400
( A )
(A) Pressure gauge hose
(B) Hole in toe board (blank cap hole)
(C) Brake pedal
4) Remove the test plug and install the ST instead.
ST 498897200
(A) Test plug
5) Connect the ST1 with ST2.
ST1 498897200
ST2 498575400
6) Check for duty ratio changes by opening and
closing the throttle valve using SUBARU Select
Monitor.
Range
position
2
(HOLD
switch
ON)
R
D
4AT-38
OIL PRESSURE GAUGE
ASSY
( B )
( C )
OIL PRESSURE GAUGE
ADAPTER
(A)
OIL PRESSURE GAUGE
ADAPTER
OIL PRESSURE GAUGE
ASSY
Standard line pressure
Line pres-
Throttle
sure duty
position
ratio (%)
5 Full open
5 Full open
95 Full closed
(3.1 — 4.2, 44 — 60)
AT-00019
AT-02379
Line pressure
2
kPa (kg/cm , psi)
1,130 — 1,275
(11.5 — 13.0,
164 — 185)
1,520 — 1,716
(15.5 — 17.5,
220 — 249)
300 — 410