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Progressive Power Steering Testing

  1. Turn ignition on. Check condition of "ENGINE" fuse. If fuse is okay, go to step 2). If fuse is not okay, replace it. If fuse checks satisfactory but system is still malfunctioning, check for short or open in wire harness between fuse and terminal "+B". See Fig 1.
  2. Disconnect PPS connector. Check that there is battery voltage between terminal "+B" and ground. If voltage is present, proceed to step 3). If voltage is not present, check for open between fuse and terminal "+B".
    Fig 1: Progressive Power Steering ECM Connector
    G59082Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. Check for continuity between computer terminal "GND" and ground. If continuity is present, proceed to step 4). If continuity is not present, check for open between terminal "GND" and body ground.
  4. Raise and support vehicle. Connect a volt/ohmmeter between computer terminals "SPD" and "GND". Spin the rear wheels and check that continuity changes from open to closed as the wheel turns.
  5. If circuit opens and closes properly, proceed to step 6). If circuit does not open and close properly, check for open or short between the speed sensor and terminal "SPD". If circuit checks okay, proceed to step 7) to test the speed sensor.
  6. Check that there is NO continuity between connector terminal "SOL+" and "SOL-" on solenoid side connector. If there is no continuity, proceed to step 9). If there is continuity, check for short between terminals "SOL+" and "SOL-" or for a faulty solenoid. Proceed to step 10).
  7. Remove combination meter from instrument panel. On models with analog meter, unplug connector "B" (middle connector). Check that there is continuity between terminals "B4" and "B7" 4 times per revolution of the wheels. If not, replace speed sensor.
  8. On models with digital combination meter, connect Harness Adapter (09082-00100 ) to combination meter and wiring harness. Attach volt/ohmmeter to terminals "4P" and "E2" of harness adapter. If voltage does not fluctuate between zero and one volt as wheels are turned, replace speed sensor.
  9. Measure resistance between terminals "SOL+" and "SOL-". Resistance should be 7.4-8.0 ohms. If resistance is correct, proceed to step 10). If resistance is not within specification, check for open in circuit between terminals "SOL+" and "SOL-".
  10. Check function of ECM. See ECM TESTING  in this article. If ECM tests satisfactory, proceed to step 11). If ECM tests unsatisfactory, replace ECM.
  11. Turn steering wheel to full lock position. Connect gauge to steering system as in HYDRAULIC PRESSURE TESTING . Apply battery voltage to solenoid terminals "SOL+" and "SOL-". Turn solenoid on and off by connecting and disconnecting battery voltage.
  12. Fluid pressure should fluctuate as voltage is applied and removed. If fluctuation is present, steering gear is faulty. Replace steering gear.
  13. If no fluctuation is present, check for clogged hydraulic lines or low fluid level. If fluid level is okay and hydraulic lines are not clogged, but system is still malfunctioning, replace solenoid.
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