Fluid Pressure Check

1. Disconnect pressure line joint using power steering line wrench tool No. 09631-22020, or equivalent.
2. Connect the gauge side of a suitable pressure gauge to the pump side and the valve side of gauge to gear housing, Fig. 1.

Fig. 1 Oil Pressure Gauge Connected To Power Steering Pump:

3. Bleed power steering system as outlined under "System Service.
4. Check and adjust fluid level.
5. Raise fluid temperature by turning the steering wheel from stop to stop. Fluid temperature should be 176°F.
6. Start and run engine.
7. Minimum fluid pressure reading with valve closed should be 1067 psi on SC300, SC400 and 1993-94 LS400 models, 1138 psi on 1995-96 LS400 models, 1280 psi on GS300 models, and 1323 psi on ES300 models. Do not keep valve closed for more than 10.0 seconds or allow fluid temperature become too high.
8. If pressure is low, repair or replace the power steering pump.
9. With valve open fully, check and record pressure reading with engine at 1000 RPM.
10. With valve open fully, check and record pressure reading with engine at 3000 RPM.
11. Ensure there is 71 psi or less difference in pressure between the 1000 RPM and 3000 RPM checks. If difference is excessive, repair or replace the flow control valve of the pump.
12. Check pressure reading with steering wheel turned to full stop position as follows:
a. Ensure pressure gauge valve is fully open and the engine idling.
b. Minimum pressure with steering wheel turned to full stop should be 1067 psi on SC300, SC400 and 1993-94 LS400 models, 1138 psi on 1995-96 LS400 models, 1280 psi on GS300 models, and 1323 psi on ES300 models. If pressure is low, the gear housing has an internal leak and must be repaired or replaced. Do not keep valve on gauge closed longer than 10.0 seconds or allow fluid temperature to become too high.
13. Remove pressure gauge from system. Bleed system and check fluid level.
14. Measure steering effort as follows:
a. Remove steering wheel pad as necessary, then center steering wheel and run engine at idle.
b. Using a suitable spring gauge, measure steering wheel effort in both directions.
c. If steering wheel effort is not less than 9 ft. lb. on ES300, SC300 and SC400 models, 8.8 lbs. on 1993-94 LS400 models and 61 in. lb. on GS300 and 1995-96 LS400 models, repair or replace the power steering unit. Consider tire type, pressure and contact surface when making your diagnosis.
d. Disconnect solenoid connector.
e. Measure steering effort as previously described.
f. Maximum steering effort should not exceed 43 in. lb. on ES300 models, 115 in. lb. on GS300 models, 15.4 ft. lb. on 1993-94 LS400 models, 9 ft. lb. on 1995-96 LS400 models and 17 ft. lb. on SC300 and SC400 models. If steering effort is not more than previous reading, check solenoid.