Power Steering Flow And Pressure - Electro-Hydraulic Power Steering

POWER STEERING FLOW AND PRESSURE - ELECTRO-HYDRAULIC POWER STEERING (EHPS)

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The following procedure is used to test the operation of the power steering system on the vehicle (equipped with EHPS). This test provides the Gallons Per Minute (GPM) or the flow rate of the power steering pump along with the maximum relief pressure. Perform this test any time a power steering system problem is present. This test determines if the power steering pump or power steering gear is not functioning properly. The following pressure and flow test is performed using Power Steering Kit , Hose from Power Steering Analyzer Adapter Kit , Hose , and Power Steering Analyzer Adapter

FLOW AND PRESSURE TEST

1. Raise and support the vehicle Maintenance.
2. Remove the front skid plate Front
3. Assemble Power Steering Analyzer as follows:
a. Gauge end (inlet) of Flow Meter And Gauge - Hose (3), Adapter (2).
b. Valve end (outlet) of Flow Meter And Gauge - Hose (6), Adapter (5).
4. Remove power steering pressure line retaining bolt from power steering pump. Separate pressure line fitting from power steering pump.
5. Connect Adapter (2) to pressure fitting on power steering pump. Tighten retaining bolt to 10 Nm (89 in. lbs.).
6. Connect power steering pressure hose to Adapter Fitting (5). Tighten retaining bolt to 10 Nm (89 in. lbs.).
7. Open the test valve completely.
8. Start the engine and idle long enough to circulate power steering fluid through the flow/pressure test gauge and to get air out of the fluid. Then shut off engine.
9. Check the fluid level, add fluid as necessary. Start the vehicle and allow it to idle.
10. The gauge should read below 862 kPa (125 psi), if above, inspect the hoses for restrictions and repair as necessary.

NOTE: Always test for and repair Diagnostic Trouble Codes (DTCs) prior to replacement of the Electro-Hydraulic Power Steering (EHPS) pump. The EHPS pump will not vary output if there are communication DTCs.

11. Record the flow meter reading (GPM) at idle with no steering wheel movement, and again while turning the wheel as fast as possible. The readings should be within specifications. If the readings are below specifications, replace the power steering pump.

CAUTION: The following test procedure involves testing maximum pump pressure output and flow control valve operation. Do not leave the valve closed for more than three seconds as the pump could be damaged.

12. Close the valve fully three times and record the highest pressure indicated each time. All three readings must be above specifications and within 345 kPa (50 psi) of each other.
- If the pressures are above specifications but not within 345 kPa (50 psi) of each other, replace the pump.
- If the pressures are within 345 kPa (50 psi) of each other but below specifications, replace pump.

CAUTION: Do not force the pump to operate against the stops for more than 2 to 3 seconds at a time because, pump damage will result.

13. Open the test valve and turn the steering wheel to the extreme left and right positions three times against the stops. Record the highest pressure reading at each position. Compare the readings and if the pressure readings are not within 345 kPa (50 psi) of each other, the gear is leaking internally and must be replaced. The initial reading will be near relief pressure, then drop approximately 689 kPa (100 PSI).
PUMP SPECIFICATION