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Home >> Dodge and Ram >> 2007 >> Magnum SXT, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Checking For Intermittent DTC, Component & System Checks, Symptom Tests >> *Checking The Engine Coolant Temperature Sensor Operation >> Diagnostic Test
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Diagnostic Test

  1. 1) ENGINE COOLANT TEMPERATURE SENSOR WIRING OR CONNECTORS 
    NOTE: Diagnose and repair any ECT circuit DTCs before proceeding with this test.
    NOTE: Allow the engine to cool to ambient temperature before proceeding.

    Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Engine Coolant Temperature sensor(s) and the PCM.

    Look for any chafed, pierced, pinched, or partially broken wires.

    Look for broken, bent, pushed out or corroded terminals.

    Turn the ignition on.

    Monitor the scan tool data relative to the sensor(s) and wiggle test the wiring and connectors.

    Look for the data to change or for a DTC to set during the wiggle test.

    Were any problems found? 

    Yes 

    1. Repair as necessary in accordance with the Service Information.
    2. Perform *PCM VERIFICATION TEST .

    No 

    1. Go to step  2).
  2. 2) ENGINE COOLANT LEVEL AND CONDITION 
    WARNING: Make sure the engine cooling system is cool before removing the pressure cap or any hose. The cooling system is pressurized when hot. Failure to follow these instructions can result in personal injury including extreme burns, scalding, or death.

    Check the engine coolant level and the condition of the engine coolant. Refer to COOLING .

    Were any problems found? 

    Yes 

    1. Repair as necessary in accordance with the Service Information.
    2. Perform *PCM VERIFICATION TEST .

    No 

    1. Go to step  3).
  3. 3) THERMOSTAT 
    WARNING: Make sure the engine cooling system is cool before removing the pressure cap or any hose. The cooling system is pressurized when hot. Failure to follow these instructions can result in personal injury including extreme burns, scalding, or death.

    Using the appropriate service information, determine the proper opening temperature of the thermostat.

    With the scan tool, read the Engine Coolant Temperature Sensor value. If the engine was allowed to cool completely, the value should be approximately equal to the ambient temperature.

    Monitor the sensor value on the scan tool.

    Start the engine.

    WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.
    NOTE: The thermostat should not open until the engine reaches the temperature specified in the Service Information.

    Were any problems found? 

    Yes 

    1. Repair as necessary in accordance with the Service Information.
    2. Perform *PCM VERIFICATION TEST .

    No 

    1. Go to step  4).
  4. 4) ENGINE COOLANT TEMPERATURE SENSOR 
    NOTE: Allow the engine to cool to ambient temperature before proceeding.
    WARNING: Make sure the engine cooling system is cool before removing the pressure cap or any hose. The cooling system is pressurized when hot. Failure to follow these instructions can result in personal injury including extreme burns, scalding, or death.

    With the scan tool, read the Engine Coolant Temperature Sensor value. If the engine was allowed to cool completely, the value should be approximately equal to the ambient temperature.

    Monitor the sensor value on the scan tool and the actual coolant temperature with a thermometer.

    Start the engine.

    WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.
    NOTE: The sensor value transition should be smooth as the engine reaches operating temperature. The thermometer reading and the coolant temperature value on the scan tool should remain relatively close.

    Were any problems found? 

    Yes 

    1. Go to step  5).
    2. Perform *PCM VERIFICATION TEST .

    No 

    1. Test complete.
  5. 5) (K2) ECT SIGNAL CIRCUIT HIGH RESISTANCE 
    Fig 1: Checking ECT Signal Circuit
    GC0052651Courtesy of CHRYSLER LLC

    Turn the ignition off.

    CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 along with the #8815-1 to perform the diagnosis.

    Using a voltmeter, perform a voltage drop test by backprobing the (K2) ECT Signal circuit at the Engine Coolant Temperature Sensor harness connector and by probing the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so that positive polarity is displayed on the voltmeter.

    WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

    Start the engine.

    Is the voltage below 0.5 volts? 

    Yes 

    1. Go to step  6).

    No 

    1. Repair the (K2) ECT Signal circuit for excessive resistance.
    2. Perform *PCM VERIFICATION TEST .
  6. 6) (K900) SENSOR GROUND CIRCUIT HIGH RESISTANCE 
    Fig 2: Checking Sensor Ground Circuit
    GC0052652Courtesy of CHRYSLER LLC

    Turn the ignition off.

    CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 along with the #8815-1 to perform the diagnosis.

    Using a voltmeter, perform a voltage drop test by backprobing the (K900) Sensor Ground circuit at the Engine Coolant Temperature Sensor harness connector and by probing the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so that positive polarity is displayed on the voltmeter.

    WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

    Start the engine.

    Is the voltage below 0.5 volts? 

    Yes 

    1. Go to step  7).

    No 

    1. Repair the (K900) Sensor Ground circuit for excessive resistance.
    2. Perform *PCM VERIFICATION TEST .
  7. 7) ENGINE COOLANT TEMPERATURE SENSOR 

    Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Engine Coolant Temperature Sensor and the Powertrain Control Module (PCM).

    Look for any chafed, pierced, pinched, or partially broken wires.

    Look for broken, bent, pushed out or corroded terminals.

    Refer to any Technical Service Bulletins that may apply.

    Were any problems found? 

    Yes 

    1. Repair as necessary.
    2. Perform *PCM VERIFICATION TEST .

    No 

    1. Replace the Engine Coolant Temperature Sensor.
    2. Perform *PCM VERIFICATION TEST .
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