Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Ford >> 1987 >> Bronco II RWD, Standard >> Repair and Diagnosis >> Engine Performance >> System >> CEC Diagnosing & Testing >> Circuit Tests >> Test P - Power Steering Pressure Switch (PSPS)

Test P - Power Steering Pressure Switch (PSPS)

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: idle speed/throttle stop adjustment, binding throttle shaft/linkage or cruise control linkage.

  1. Code 52 Displayed. Turn key off and wait 10 seconds. Disconnect PSPS. Install a jumper wire between PSPS circuit and signal return at harness. Repeat KEY ON/ENGINE OFF SELF-TEST. If code 52 is not displayed, replace PSPS and repeat QUICK TEST . If code 52 is still displayed, go to next step.
  2. Turn key off and wait 10 seconds. Disconnect PSPS and ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale and measure resistance between test pin 46 and signal return at PSPS connector. Also measure resistance between test pin 3 (pin No. 24 on 2.3L HSC CFI, 3.0L EFI Car, 4.9L/5.0L EFI Truck) and PSPS circuit at connector. If both readings are less than 5 ohms, replace ECA. Repeat QUICK TEST . If both readings are more than 5 ohms, repair open in circuit. Repeat QUICK TEST .
  3. Connect tachometer and start engine, allowing it to idle in Park or Neutral. Disconnect PSPS circuit at switch. If RPM increases, replace PSPS. If RPM does not increase, go to next step.
  4. Turn key off and wait 10 seconds. Disconnect PSPS and ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin 3 and test pin 46. If reading is less than 5 ohms, repair short in harness. If reading is more than 5 ohms, replace ECA. Repeat QUICK TEST .
  5. Be sure steering wheel was turned 1/2 turn after engine ID code, but before dynamic response code. If not, repeat QUICK TEST . If wheel was turned, go to next step. Be sure wheels are centered.
  6. Turn key off, wait 10 seconds. Disconnect PSPS and perform KEY ON/ENGINE OFF SELF-TEST. If code 52 is present, go to step 8). If not, go to next step.
  7. Turn key off, wait 10 seconds. Remove harness from 60 pin connector and check for damaged pins or loose wires. Service as necessary. Disconnect PSPS and ECA. Install breakout box. Set DVOM on 200,000-ohm scale. Measure resistance between pins No. 46 and 24 at breakout box. If resistance reading is 10,000 ohms or less service PSPS short and repeat QUICK TEST . If resistance reading is not 10,000 ohms or less replace ECA and repeat QUICK TEST .
  8. Turn key off, wait 10 seconds. Install breakout box with ECA and PSPS connected. Set DVOM on 200-ohm scale. Turn key on and measure resistance from test pins No. 24 to 46. Start engine. If resistance is less than 10 ohms between KEY ON/ENGINE OFF and engine running, go to next step. If more, go to step 11).
  9. Install breakout box, ECA and PSPS. Set DVOM on 200-ohm scale. With engine idling, measure resistance from test pins No. 24 to 46. Turn steering wheel 1/2 turn and return to center. If resistance changes from less than 10 ohms to infinity (indicating PSPS opening), then returns to 10 ohms or less when steering wheel is returned to center position, PSPS system is okay. If not, go to next step.
  10. At this point there are only 2 possible causes for the original code 52 engine running:
    • PSPS switch that will not open.
    • Low available hydraulic pressure.

    Turn key off, wait 10 seconds. Substitute original PSPS with a known good unit. Run ENGINE RUNNING SELF-TEST, turning steering 1/2 turn during test. If code 52 is still present, power steering system is emitting high pressure. If code 52 is not present, PSPS switch is bad.

Fig 1: Power Steering Pressure Switch (PSPS) Circuit
G11089
scientia non olet · About Mike's Workshop Manuals