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HOMESERVICE MANUALSFORD2005CROWN VICTORIA SPECIAL EDITIONREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1655 (ENGINE CONTROLS - PINPOINT TESTS - (HYBRID) - FAULT CODE INDEX, PINPOINT TESTS A - DN)PINPOINT TEST DN: MOTOR ELECTRONICS COOLANT TEMPERATURE (MECT) SENSORTEST PROCEDURE
2005 Ford Crown Victoria Special Edition

Test Procedure

2005 Ford Crown Victoria Special EditionSECTION Test Procedure
WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
  1. DN1 DTCS P0A00, P0A01, P0A02, P0A03 AND P0A7C: CHECK FOR SELF-TEST DTCS 

    Are any of the following DTCs present during PCM or TCM self-test: P0A00, P0A01, P0A02, P0A03, or P0A7C? 

    Yes No
    For DTCs P0A00 and P0A7C, GO to  DN2.
    For DTC P0A01, GO to  DN14.
    For KOEO and KOER DTC P0A02, GO to  DN9.
    For KOEO and KOER DTC P0A03, GO to  DN5.
    For continuous memory DTCs P0A02 or P0A03, GO to  DN11.    		 Unable to duplicate or identify the fault at this time.
    The concern is elsewhere. RETURN to SYMPTOM CHARTS for further direction.
  2. DN2 DTCS P0A00 AND P0A7C: VISUALLY INSPECT THE MOTOR ELECTRONICS COOLING SYSTEM 
    NOTE: Repair any motor electronics coolant pump (MECP) DTCs before proceeding.
    • Visually inspect the motor electronics cooling system for leaks, pinched hoses, restricted radiator air flow, correct coolant level, fan operation, and loose electrical connections.

    Is the motor electronics cooling system OK? 

    Yes No
    GO to  DN3. Refer to TRANSAXLE/TRANSMISSION COOLING - HYBRID to diagnose the motor electronics cooling system (MECS) overheating concern.
  3. DN3 ROAD TEST THE VEHICLE AND MONITOR THE MECT_V PID 
    NOTE: Refer to TEMPERATURE SENSOR VOLTAGE AND RESISTANCE SPECIFICATIONS  for voltage specifications.
    • Access the PCM and monitor the MECT_V PID.
    • Road test the vehicle with heavy loads on the vehicle such as the A/C on MAX, the headlamps on, and the rear window defroster on.

    Does the MECT sensor operate in the normal temperature range? 

    Yes No
    GO to  DN11. GO to  DN4.
  4. DN4 CHECK THE RESISTANCE OF THE MECT SENSOR 
    NOTE: Refer to TEMPERATURE SENSOR VOLTAGE AND RESISTANCE SPECIFICATIONS  for temperature versus resistance specifications.
    • MECT Sensor connector disconnected.
    • Measure the resistance between:
      ( + ) MECT Sensor Connector, Component Side ( - ) MECT Sensor Connector, Component Side
      MECT - Pin 1 SIGRTN-C - Pin 2

    Does the resistance of the MECT sensor match the ambient engine coolant temperature? 

    Yes No
    Refer to TRANSAXLE/TRANSMISSION COOLING - HYBRID to diagnose the motor electronics cooling system (MECS) overheating concern. INSTALL a new MECT sensor.
  5. DN5 DTC P0A03: CHECK THE MECT CIRCUIT FOR A SHORT TO PWR IN THE HARNESS 
    • MECT Sensor connector disconnected.
    • PCM connector disconnected.
    • Key ON, engine OFF.
    • Measure the voltage between:
      ( + ) MECT Sensor Connector, Harness Side ( - )
      MECT - Pin 1 Ground

    Is the voltage less than 5 V? 

    Yes No
    Key in OFF position.
    GO to  DN6.    		 Key in OFF position. REPAIR the short circuit to PWR.
    CHECK MECT sensor for damage.
    GO to  DN6.
  6. DN6 CHECK THE RESISTANCE OF THE MECT SENSOR WITH THE ENGINE OFF 
    NOTE: Refer to TEMPERATURE SENSOR VOLTAGE AND RESISTANCE SPECIFICATIONS  for the resistance specifications.
    • Key in OFF position.
    • Measure the resistance between:
      ( + ) MECT Sensor Connector, Component Side ( - ) MECT Sensor Connector, Component Side
      MECT - Pin 1 SIGRTN-C - Pin 2

    Is the resistance within specification? 

    Yes No
    Key in OFF position.
    GO to  DN7.    		 Key in OFF position. INSTALL a new MECT sensor.
  7. DN7 CHECK THE SIGNAL AND SIGRTN CIRCUITS FOR AN OPEN IN THE HARNESS 
    • Key in OFF position.
    • Measure the resistance between:
      ( + ) MECT Sensor Connector, Harness Side ( - ) PCM Connector, Harness Side
      MECT - Pin 1 MECT - Pin T3
      SIGRTN-C - Pin 2 SIGRTN-C - Pin B41

    Is each resistance less than 5 ohms? 

    Yes No
    GO to  DN8. REPAIR the open circuit.
  8. DN8 CHECK THE SENSOR SIGNAL FOR A SHORT TO VREF 
    • Key in OFF position.
    • Measure the resistance between:
      ( + ) PCM Connector, Harness Side ( - ) PCM Connector, Harness Side
      MECT - Pin T3 VREF - Pin B40

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  DN17. REPAIR the short circuit to VREF.
  9. DN9 DTC P0A02: SIMULATE AN OPPOSITE SIGNAL TO THE PCM 
    • MECT Sensor connector disconnected.
    • Key ON, engine OFF.
    • Access the PCM and monitor the MECT_V PID.

    Is the voltage greater than 4.2 V? 

    Yes No
    Key in OFF position. INSTALL a new MECT sensor. Key in OFF position.
    GO to  DN10.
  10. DN10 CHECK THE SENSOR SIGNAL FOR A SHORT TO GROUND 
    • PCM connector disconnected.
    • Measure the resistance between:
      ( + ) MECT Sensor Connector, Harness Side ( - ) PCM Connector, Harness Side
      MECT - Pin 1 SIGRTN-C - Pin B41
    • Measure the resistance between:
      ( + ) PCM Connector, Harness Side ( - ) Vehicle Battery
      MECT - Pin T3 Negative terminal

    Are the resistances greater than 10,000 ohms? 

    Yes No
    GO to  DN17. REPAIR the short circuit to GND.
  11. DN11 CONTINUOUS MEMORY DTCS P0A00, P0A02, P0A03 AND P0A7C: CHECK THE MECT SENSOR FOR AN INTERMITTENT CONCERN 
    • Key ON, engine OFF.
    • Access the PCM and monitor the MECT_V PID.
    • While observing the PID, carry out the following:
      • Tap on the sensor to simulate road shock.
      • Wiggle the sensor connector.

    Does the MECT_V PID voltage indicate a fault in the MECT sensor? 

    Yes No
    DISCONNECT and INSPECT the connector.
    If OK, INSTALL a new MECT sensor.    		 GO to  DN12.
  12. DN12 CHECK THE MECT CIRCUIT FOR AN INTERMITTENT CONCERN 
    • Access the PCM and monitor the MECT_V PID.
    • While observing the PID, wiggle, shake, and bend small sections of the wiring harness working from the sensor to the PCM.

    Does the MECT_V PID voltage indicate a fault in the MECT circuit? 

    Yes No
    ISOLATE the fault and REPAIR as necessary.
    CARRY OUT the Comprehensive Component Monitor Drive Cycle. REFER to ON BOARD DIAGNOSTIC (OBD) DRIVE CYCLE .    		 GO to  DN13.
  13. DN13 CHECK THE PCM AND VEHICLE HARNESS CONNECTORS 
    • PCM connector disconnected.
    • MECT Sensor connector disconnected.

    Are the connectors and terminals OK? 

    Yes No
    Unable to duplicate or identify the fault at this time.
    GO to Pinpoint Test Z .    		 REPAIR as necessary.
  14. DN14 DTC P0A01: CHECK FOR THE PRESENCE OF PCM DTCS P0A00, P0A02, P0A03, P0A7C 
    NOTE: The TCM DTC P0A01 may be stored as a result of the MECT sensor or a corresponding circuit concern.

    The PCM DTCs P0A00, P0A02, P0A03, or P0A7C present along with a P0A05 indicate the MECT sensor or harness concern.

    Are any of the above listed DTCs present? 

    Yes No
    DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS . GO to  DN15.
  15. DN15 VERIFY THAT THE HARD FAULT IS PRESENT 
    NOTE: Clearing the TCM DTCs will erase any TCM recorded freeze frame data. Make sure to record any TCM freeze frame information before proceeding any further. Refer to the diagnostic tool instruction manual for freeze frame PID menu.
    • Clear and retrieve the TCM continuous DTCs.

    Is DTC P0A01 present? 

    Yes No
    GO to  DN16. Unable to duplicate or identify the fault at this time.
  16. DN16 CHECK THE TCM MECT PID 
    • Key ON, engine OFF.
    • Access the TCM and monitor the MECT PID.
    • Start the engine using the engine running diagnostic mode. Refer to DIAGNOSTIC MODES .
    • Turn on all optional electrical loads.
    • Idle the engine for 5 minutes with the load on and monitor the MECT PID.

    Does the MECT PID temperature increase by at least 1 degree? 

    Yes No
    Key in OFF position. INSTALL a new transaxle assembly. Key in OFF position.
    GO to  DN17.
  17. DN17 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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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.