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Diagnostic Test

  1. ACTIVE DTC 
    1. Ignition on, engine not running.
      NOTE: If this code sets during extreme ambient temperatures, improper installation of a block heater could be the cause of this DTC.
    2. With a scan tool, select View DTCs.
    3. Diagnose all other ECT and Cooling System codes before continuing.

      Is the DTC Active at this time?

      Yes 

      • Go to step  2

      No 

  2. LOW COOLANT LEVEL 
    NOTE: If an Engine Coolant Temperature (ECT) DTC is set along with this code, diagnose the ECT DTC first.
    NOTE: Inspect the ECT Sensor terminals and related PCM terminals. Ensure the terminals are free from corrosion and damage.
    NOTE: The best way to diagnose this DTC is to allow the vehicle to sit overnight outside in order to have a totally cold soaked engine.
    NOTE: Extremely cold outside ambient temperatures may have caused this DTC to set.
    NOTE: Need to make sure that no Cooling System DTCs are set or changes that would make the warm up much slower or much faster: broken water pump can set this, addition of aftermarket auxiliary cooler can set this DTC.
    WARNING: Never open the cooling system when the engine is hot. The system is under pressure. Failure to follow these instructions can result in personal injury or death. Allow the engine to cool before opening the cooling system.
    1. Inspect the coolant system for proper level and condition.

      Is the coolant level and condition OK?

      Yes 

      • Go to step  3

      No 

  3. THERMOSTAT 
    NOTE: This test works best if performed on a cold engine (cold soak).
    1. Ignition on, engine not running.
    2. With a scan tool, read the Eng Coolant Tmp Deg value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.
      NOTE: If engine coolant temperature is above 82°C (180°F), allow the engine to cool until 65°C (150°F) is reached.
    3. Start the Engine.
    4. During engine warm-up monitor the Eng Coolant Tmp Deg value. The temp deg value change should be a smooth transition from start up to normal operating temp 82°C (180°F). Also monitor the actual coolant temperature with a thermometer.
      NOTE: As the engine warms up to operating temperature, the actual coolant temperature (thermometer reading) and the Eng Coolant Tmp Deg on the scan tool should stay relatively close to each other.
    5. Using the appropriate service information, determine the proper opening temperature of the thermostat.

      Did the thermostat open at the proper temperature?

      Yes 

      • Go to step  4

      No 

  4. ECT SENSOR 
    Fig 1: Checking ECT Signal Circuit
    GC0106663Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Disconnect the ECT Sensor harness connector.
    3. With a scan tool, read the ECT voltage.
    4. Connect a jumper between the (K2) ECT Signal circuit and the (K900) Sensor ground circuit in the ECT Sensor harness connector.

      Is the voltage below 1.0 volt with the jumper wired installed?

      Yes 

      No 

      • Go to step  5
  5. (K2) ECT SIGNAL CIRCUIT SHORTED TO VOLTAGE 
    Fig 2: Checking ECT Sensor Circuit
    GC0120336Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Disconnect the C2 PCM harness connector.
    3. Ignition on, engine not running.
    4. Measure the voltage on the (K2) ECT Signal circuit in the ECT Sensor harness connector.

      Is there any voltage present?

      Yes 

      No 

      • Go to step  6
  6. (K2) ECT SIGNAL CIRCUIT OPEN 
    Fig 3: Checking ECT Signal Circuit
    GC0120339Courtesy of CHRYSLER LLC
    1. 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 PCM Pinout Box 8815 to perform diagnosis.
    2. Measure the resistance of the (K2) ECT Signal circuit from the ECT Sensor harness connector to the appropriate terminal of special tool #8815.

      Is the resistance below 5.0 ohms?

      Yes 

      • Go to step  7

      No 

  7. (K900) SENSOR GROUND CIRCUIT OPEN 
    Fig 4: Checking ECT Ground Circuit
    GC0120340Courtesy of CHRYSLER LLC
    1. Measure the resistance of the (K900) Sensor ground circuit from the ECT Sensor harness connector to the appropriate terminal of special tool #8815.

      Is the resistance below 5.0 ohms?

      Yes 

      • Go to step  8

      No 

  8. (K2) ECT SIGNAL CIRCUIT SHORTED TO GROUND 
    Fig 5: Checking ECT Signal Circuit
    GC0120337Courtesy of CHRYSLER LLC
    1. Measure the resistance between ground and the (K2) ECT Signal circuit in the ECT Sensor harness connector.

      Is the resistance below 100 ohms?

      Yes 

      No 

      • Go to step  9
  9. (K2) ECT SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT 
    Fig 6: Checking ECT Signal Circuit
    GC0106666Courtesy of CHRYSLER LLC
    1. Measure the resistance between the (K2) ECT Signal circuit and the (K900) Sensor ground circuit in the ECT Sensor harness connector.

      Is the resistance below 5.0 ohms?

      Yes 

      No 

      • Go to step  10
  10. POWERTRAIN CONTROL MODULE (PCM) 
    1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the ECT Sensor and the Powertrain Control Module (PCM).
    2. Look for any chafed, pierced, pinched, or partially broken wires.
    3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the ECT Sensor and Powertrain Control Module connectors.
    4. Refer to any Technical Service Bulletins that may apply.

      Were there any problems found?

      Yes 

      No 

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