Hydraulic System Testing

With engine off, disconnect pressure hose from pump. Install Power Steering Tester (J-29877-A ) between power steering pump and steering unit. See Fig 1 .

Fig 1: Testing Power Steering System Fluid Pressure
Courtesy of ISUZU MOTOR CO.
Bleed system by holding gauge beneath fluid reservoir with shut-off valve open. With engine idling, check fluid level in reservoir. Refill reservoir if necessary.
If steering system still malfunctions, start engine. Turn steering wheel from lock-to-lock several times, until fluid has reached a temperature of 122°-140° F (50°-60° C). Hold steering wheel at lock with pressure gauge stop valve open.
CAUTION: DO NOT hold steering wheel at lock position more than 5 seconds.
If fluid pressure is over 1280 psi (90 kg/cm² ), pump is defective. If fluid pressure is less than 1209 psi (85 kg/cm² ), return front wheels to straight ahead position and close pressure gauge stop valve.
Hold engine at 1500 RPM and check pressure gauge reading. If pressure reading is 1209-1280 psi (85-90 kg/cm² ), problem is with steering gear box. If reading is less than 1209 psi (85 kg/cm² ), problem is with oil pump.
CAUTION: DO NOT leave shutoff valve closed more than 15 seconds as it may cause damage to pump.