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HOMESERVICE MANUALSMERCURY2010MARINER PREMIER, 2.5 7, FWDREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - PINPOINT TEST DL: CYLINDER HEAD TEMPERATURE (CHT) SENSOR THROUGH PINPOINT TEST DX: ENGINE COOLANT TEMPERATURE (ECT) SENSOR - (EXCEPT DIESEL & HYBRID)PINPOINT TEST DX: ENGINE COOLANT TEMPERATURE (ECT) SENSORTEST PROCEDURE
2010 Mercury Mariner Premier, 2.5 7, FWD

Test Procedure

2010 Mercury Mariner Premier, 2.5 7, FWDSECTION Test Procedure
  1. DX1 CHECK FOR DIAGNOSTIC TROUBLE CODES (DTCS) 

    Are DTCs P0116, P0117, P0118, P0119, P0125, P0128, P0217, P1116, or P1117 present? 

    Yes No
    For continuous memory DTC P0116, GO to  DX14.
    For KOEO and KOER DTC P0117, GO to  DX12.
    For continuous memory DTCs P0117, P0118, P0119, or P1117, GO to  DX16.
    For KOEO and KOER DTC P0118, GO to  DX8.
    For continuous memory DTCs P0125, or P0128, GO to  DX19.
    For DTC P0217, GO to  DX21.
    For KOEO and KOER DTC P1116, GO to  DX2.    		 For all others, GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .
  2. DX2 DTC P1116: CHECK THE COOLING SYSTEM 
    WARNING: TO AVOID PERSONAL INJURY DO NOT UNSCREW THE COOLANT PRESSURE RELIEF CAP WHILE THE ENGINE IS OPERATING OR HOT. THE COOLING SYSTEM IS UNDER PRESSURE. STEAM AND HOT LIQUID CAN COME OUT FORCEFULLY WHEN THE CAP IS LOOSENED SLIGHTLY. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY.
    • The DTC indicates the temperature sensor is out of self-test range. The engine is not at normal operating temperature.
    • Check the vehicle coolant level.

    Is the cooling system OK? 

    Yes No
    GO to  DX3. REFER to the appropriate Engine Cooling article for loss of coolant diagnosis.
    REPAIR as necessary.
    CLEAR the DTCs. REPEAT the self-test.
  3. DX3 CHECK IF THE VEHICLE ENGINE STARTS 
    • Attempt to start the engine.

    Does the engine start and run normally? 

    Yes No
    GO to  DX6. GO to  DX4.
  4. DX4 CHECK THE RESISTANCE OF THE ECT SENSOR WITH THE ENGINE OFF 
    NOTE: Refer to the chart at the beginning of this test for the resistance specifications.
    • Ignition OFF.
    • ECT Sensor connector disconnected.
    • Measure the resistance between:
      (+) ECT Sensor Connector, Component Side (-) ECT Sensor Connector, Component Side
      ECT - Pin 1 SIGRTN - Pin 2

    Is the resistance within specification? 

    Yes No
    GO to  DX5. INSTALL a new ECT sensor. REFER to the appropriate Electronic Engine Controls article .
    CLEAR the DTCs. REPEAT the self-test.
  5. DX5 CHECK THE CIRCUIT FROM THE MODULE TO THE COMPONENT 
    NOTE: Refer to the chart at the beginning of this test for the resistance specifications.
    • ECT Sensor connector connected.
    • Ignition ON, engine OFF.
    • Access the PCM and monitor the ECT PID.
    • Using the data collected from the previous step, compare temperature resistance measured at the sensor to the PID temperature voltage measured at the PCM.

    Does the measured value at the sensor agree with the measured PID voltage value at the PCM? 

    Yes No
    RETURN to SYMPTOM CHARTS for further direction. GO to  DX10.
  6. DX6 CHECK THE ECT SENSOR OPERATION 
    • Run the engine until the engine temperature stabilizes.
    • Verify the upper radiator hose is hot and the cooling system is pressurized.
    • Repeat the KOER self-test.

    Is DTC P1116 present? 

    Yes No
    GO to  DX7. The engine temperature was not stabilized. REPAIR any other DTCs as necessary.
  7. DX7 CHECK THE RESISTANCE OF THE ECT SENSOR 
    NOTE: Refer to the chart at the beginning of this test for the resistance specifications.
    • The vehicle must be at normal operating temperature.
    • Ignition OFF.
    • ECT Sensor connector disconnected.
    • Measure the resistance between:
      (+) ECT Sensor Connector, Component Side (-) ECT Sensor Connector, Component Side
      ECT - Pin 1 SIGRTN - Pin 2

    Is the resistance within specification? 

    Yes No
    GO to  DX25. INSTALL a new ECT sensor. REFER to the appropriate Electronic Engine Controls article .
    CLEAR the DTCs. REPEAT the self-test.
  8. DX8 DTC P0118: CHECK THE ECT SIGNAL CIRCUIT 
    • The DTC indicates the sensor signal is greater than the self-test maximum.
    • ECT Sensor connector disconnected.
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) ECT Sensor Connector, Harness Side (-) ECT Sensor Connector, Harness Side
      ECT - Pin 1 SIGRTN - Pin 2

    Is the voltage between 4.5 - 5.5 V? 

    Yes No
    GO to  DX9. GO to  DX10.
  9. DX9 CHECK THE RESISTANCE OF THE ECT SENSOR WITH THE ENGINE OFF 
    NOTE: Refer to the chart at the beginning of this test for the resistance specifications.
    • Ignition OFF.
    • ECT Sensor connector disconnected.
    • Measure the resistance between:
      (+) ECT Sensor Connector, Component Side (-) ECT Sensor Connector, Component Side
      ECT - Pin 1 SIGRTN - Pin 2

    Is the resistance within specification? 

    Yes No
    GO to  DX11. INSTALL a new ECT sensor. REFER to the appropriate Electronic Engine Controls article .
    CLEAR the DTCs. REPEAT the self-test.
  10. DX10 CHECK THE SIGNAL AND SIGRTN CIRCUITS FOR AN OPEN IN THE HARNESS 
    • Ignition OFF.
    • PCM connector disconnected.
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) ECT Sensor Connector, Harness Side
      ECT - Pin E18 ECT - Pin 1
      SIGRTN - Pin E58 SIGRTN - Pin 2

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  DX25. REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
  11. DX11 CHECK THE SENSOR SIGNAL FOR A SHORT TO VREF 
    • Ignition OFF.
    • PCM connector disconnected.
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) PCM Connector, Harness Side
      ECT - Pin E18 VREF - Pin E57

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  DX25. REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
  12. DX12 DTC P0117: SIMULATE AN OPPOSITE SIGNAL TO THE PCM 
    • The DTC indicates the sensor signal is less than the self-test minimum.
    • Possible causes:
      • grounded circuit in the harness
      • incorrect harness connections
      • damaged sensor
      • damaged PCM
    • ECT Sensor connector disconnected.
    • Ignition ON, engine OFF.
    • Access the PCM and monitor the ECT PID.

    Is the voltage greater than 4.2 V? 

    Yes No
    INSTALL a new ECT sensor. REFER to the appropriate Electronic Engine Controls article .
    CLEAR the DTCs. REPEAT the self-test.    		 GO to  DX13.
  13. DX13 CHECK THE SENSOR SIGNAL FOR A SHORT TO GROUND 
    • PCM connector disconnected.
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) PCM Connector, Harness Side
      ECT - Pin E18 SIGRTN - Pin E58
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) 12 Volt Vehicle Battery
      ECT - Pin E18 Negative terminal

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  DX25. REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
  14. DX14 DTC P0116: CHECK THE RESISTANCE OF THE ECT SENSOR WITH THE ENGINE OFF 
    NOTE: Verify the engine temperature is at ambient room temperature before continuing with this test. A soak period of 6 hours may be required. Refer to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS for information concerning P0116.
RENDER: 1.0x

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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.