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Home >> Mercury >> 2006 >> Montego Base, AWD >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Pinpoint Test DK: Accelerator Pedal Position (App) Sensor Through Pinpoint Test DW: Heated Oxygen Sensor (Ho2S) - (Except Diesel & Hybrid) >> Pinpoint Test DT: Power Steering Pressure (PSP) Sensor >> Test Procedure

Test Procedure

  1. DT1 CHECK FOR DTCS 

    Are DTCs P0552, P0553, or P1550 present? 

    Yes No
    For KOEO and KOER DTCs P0552 or P0553, GO to  DT4.
    For continuous memory DTCs P0552 or P0553, GO to  DT8.
    For KOEO and KOER DTC P1550, GO to  DT2.    		 For all others, GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .
  2. DT2 DTC P1550: MAKE SURE THE STEERING WHEEL IS TURNED 

    Did you turn the steering wheel at least one half turn within 20 seconds of starting the KOER selftest? 

    Yes No
    If there are any symptoms with the power steering system (for example, lack of power assist), REFER to the appropriate STEERING SYSTEM - GENERAL INFORMATION article to continue diagnosis of steering system. If no symptoms are present with the power steering system,
    GO to  DT3.    		 REPEAT the KOER self-test.
  3. DT3 KOEO AND KOER DTCS P0552, P0553 OR P1550: CHECK THE VOLTAGE BETWEEN VREF AND SIGRTN AT THE PSP SENSOR 
    • PSP Sensor connector disconnected.
    • Key ON, engine OFF.
    • Measure the voltage between:
      ( + ) PSP Sensor Connector, Harness Side ( - ) PSP Sensor Connector, Harness Side
      VREF - Pin 2 SIGRTN - Pin 1

    Is the voltage between 4 - 6 V? 

    Yes No
    GO to  DT4. GO to Pinpoint Test C .
  4. DT4 CHECK THE PSP CIRCUIT FOR AN OPEN IN THE HARNESS 
    • Key in OFF position.
    • PCM connector disconnected.
    • Measure the resistance between:
      ( + ) PSP Sensor Connector, Harness Side ( - ) PCM Connector, Harness Side
      PSP - Pin 3 PSP

    Is the resistance less than 5 ohms? 

    Yes No
    GO to  DT5. REPAIR the open circuit. CLEAR the DTCs.
    REPEAT the self-test.
  5. DT5 CHECK THE PSP CIRCUIT FOR A SHORT TO VOLTAGE IN THE HARNESS 
    • Key ON, engine OFF.
    • Measure the voltage between:
      ( + ) PSP Sensor Connector, Harness Side ( - )
      PSP - Pin 3 Ground

    Is the voltage less than 1 V? 

    Yes No
    GO to  DT6. REPAIR the short circuit. CLEAR the DTCs.
    REPEAT the self-test.
  6. DT6 CHECK THE PSP CIRCUIT FOR A SHORT TO VREF, SIGRTN AND GND IN THE HARNESS 
    • Key in OFF position.
    • Measure the resistance between:
      ( + ) PSP Sensor Connector, Harness Side ( - ) PSP Sensor Connector, Harness Side
      PSP - Pin 3 VREF - Pin 2
      PSP - Pin 3 SIGRTN - Pin 1
    • Measure the resistance between:
      ( + ) PSP Sensor Connector, Harness Side ( - )
      PSP - Pin 3 Ground

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  DT7. REPAIR the short circuit. CLEAR the DTCs.
    REPEAT the self-test.
  7. DT7 CHECK THE SENSOR OPERATION 
    • Connect a 5 amp fused jumper wire between the following:
      Point A PSP Sensor Connector, Harness Side Point B PSP Sensor Connector, Component Side
      VREF - Pin 2 VREF - Pin 2
      SIGRTN - Pin 1 SIGRTN - Pin 1
      PSP - Pin 3 PSP - Pin 3
    • Start engine and allow to idle.
    • Measure the voltage between:
      ( + ) PSP Sensor Connector, Component Side ( - )
      PSP - Pin 3 Ground
    • Observe the voltage while turning the steering wheel at least 1/2 turn right and left.

    Is the voltage reading between 0.3 and 4.7 volts and does the voltage change when the steering wheel is turned? 

    Yes No
    GO to  DT9. INSTALL a new PSP sensor. CLEAR the DTCs.
    REPEAT the self-test.
  8. DT8 CONTINUOUS MEMORY DTCS P0552 OR P0553: CHECK THE POWER STEERING PRESSURE SENSOR CIRCUIT(S) FOR INTERMITTENT CONCERNS 
    • Key ON, engine OFF.
    • Access the PCM and monitor the PSP V PID.
    • Observe the PSP V PID for an indication of a concern while carrying out the following. (a concern is indicated by a sudden change in the voltage):
      • Shake, wiggle, and bend the PSP, VREF, SIGRTN circuit(s).
      • Lightly tap on the power steering pressure sensor to simulate road shock.

    Is a concern indicated? 

    Yes No
    ISOLATE the concern. REPAIR as necessary. Unable to duplicate or identify the concern at this time.
    CLEAR the DTCs. REPEAT the self-test. GO to Pinpoint Test Z .
  9. DT9 CHECK FOR CORRECT PCM OPERATION 
    • Disconnect all the PCM connectors.
    • Visually inspect for:
      • pushed out pins
      • corrosion
    • Connect all the PCM connectors and make sure they seat correctly.
    • Carry out the PCM self-test and verify the concern is still present.

    Is the concern still present? 

    Yes No
    INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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