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Home >> Mercury >> 2005 >> Montego Base, AWD >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Pinpoint Test DK: Accelerator Pedal Position Sensor Through Pinpoint Test DX: Engine Coolant Temperature (ECT) Sensor - (Except Diesel & Hybrid) >> Pinpoint Test DT: Power Steering Pressure (PSP) Sensor >> Test Procedure

Test Procedure

  1. DT1 DTC P1550: MAKE SURE THE FOLLOWING ACTION HAS BEEN TAKEN 

    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 STEERING SYSTEM - GENERAL INFORMATION to continue diagnosis of steering system. If no symptoms are present with the power steering system, GO to  DT2. RERUN the KOER self-test.
  2. DT2 KOEO AND KOER DTCS P0552 OR P0553: CHECK THE VOLTAGE BETWEEN VREF AND SIGRTN AT THE PSP SENSOR 
    • PSP Sensor connector disconnected.
    • Key in ON position.
    • 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 V - 6 V? 

    Yes No
    Key in OFF position.
    GO to  DT3.    		 Key in OFF position.
    GO to PINPOINT TEST C STEP 1 .
  3. DT3 CHECK THE PSP CIRCUIT FOR AN OPEN IN THE HARNESS 
    • 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  DT4. REPAIR the open circuit.
  4. DT4 CHECK THE PSP CIRCUIT FOR A SHORT TO POWER IN THE HARNESS 
    • Key in ON position.
    • Measure the voltage between:
      (+) PSP Sensor Connector, Harness Side (-)
      PSP - Pin 3 Ground

    Is the voltage less than 1 V? 

    Yes No
    Key in OFF position.
    GO to  DT5.    		 REPAIR the short circuit.
  5. DT5 CHECK THE PSP CIRCUIT FOR A SHORT TO VREF, SIGRTN AND GND IN THE HARNESS 
    • 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  DT6. REPAIR the short circuit.
  6. DT6 CHECK 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
    Key in OFF position. INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . INSTALL a new PSP sensor.
  7. DT7 CONTINUOUS MEMORY DTC P0552, P0553: CHECK THE POWER STEERING PRESSURE SENSOR CIRCUIT(S) FOR INTERMITTENT CONCERNS 
    • Key in ON position.
    • Access the PCM and monitor the PSP V PID.
    • Observe the PSP V PID for an indication of a fault while completing the following: (a fault 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 fault indicated? 

    Yes No
    ISOLATE the fault
    REPAIR as necessary.    		 Key in OFF position.
    Unable to duplicate or identify the fault at this time.
    GO to PINPOINT TEST Z STEP 1 .
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