Suzuki RA410 Manual page 543

7B-16 AUTOMATIC TRANSMISSION
9) Possible causes for out-of-specification line pressure are as
follows. Check each part which is suspected to be the cause.
Test result
Fluid pressure is higher
than standard value in
each range
Fluid pressure is lower
than standard value in
each range
Fluid pressure is lower
than standard value in D
range only
Fluid pressure is lower
than standard value in R
range only
Pressure does not vary
between idle speed and
stall speed
Possible cause
Defective vacuum diaphragm
Defective vacuum hose
Defective vacuum diaphragm
Defective vacuum hose
Pressure leakage from fluid
pressure circuit
Defective oil pump
Clogged oil strainer
Leakage from D range fluid
pressure circuit
Pressure leakage at forward
clutch
Leakage from R range fluid
pressure circuit
Leakage at direct clutch,
first reverse brake
Poor sliding of pressure
regulator valve
Poor sliding of throttle valve
Disconnected vacuum hose
Clogged oil strainer