Hydraulic Pressure Tests

WARNING: This page is about a different car, the 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Perform test at normal operating fluid temperature of 122-176°F (50-80°C).

Ensure transaxle fluid is at operating temperature. Raise and support vehicle. Remove transaxle case test plugs. See Fig 1. Install hydraulic pressure gauges. Lower vehicle.
Fully apply parking brake. Block all wheels. Start engine and ensure idle speed is 650-750 RPM. Place selector lever in "D" position. Read and record pressures at idle. Fully apply brakes. Depress accelerator pedal to floor. DO NOT apply full throttle for more than 5 seconds.
Measure highest line pressure. Refer to specifications. See LINE PRESSURE SPECIFICATIONS table. Repeat test in "R" position. If pressures exceed specifications in all ranges, regulator valve or control valve in upper valve body is defective. Ensure no Throttle Position (TP) sensor-related trouble codes are present.
If pressures in both positions are lower than specifications, oil pump, regulator valve or underdrive clutch is defective. Ensure no TP sensor related trouble codes are present.
If pressure is lower than specifications in "D" position only, forward clutch is defective or "D" range circuit has a fluid leak. If pressure is lower than specifications in "R" position only, direct clutch is defective, 1st/reverse brake is defective or "R" range circuit has a fluid leak.

Fig 1: Locating Pressure Test Plugs For Testing

LINE PRESSURE SPECIFICATIONS

Engine RPM	"D" Range - psi (kg/cm² )	"R" Range - psi (kg/cm² )
Idle Speed	54-60 (3.8-4.2)	97-106 (6.8-7.5)
Stall Speed	134-150 (9.5-10.5)	256-286 (18.0-20.1)