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Home >> Jeep >> 2024 >> Gladiator Nighthawk, Part Time T/Case Control, Automatic Trans >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> 3.6L (GPEC 5) - DTCS P2172 To P2229 >> DTC Troubleshooting >> P2181 Cooling System Performance >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR OTHER DTCS 
    1. Turn the ignition on.
    2. With the scan tool, read DTCs and record on the repair order.

      Are there any Engine Coolant Temperature (ECT) Sensor DTCs active or pending?

      Yes 

      No 

      • Go To  2
  2. CHECK THE ENGINE COOLANT LEVEL AND CONDITION 
    1. Turn the ignition off.
      WARNING:

      Allow the engine to cool before opening the cooling system. The system may be under pressure. Extreme burns or scalding may result. Failure to follow these instructions can result in possible serious or fatal injury.

    2. Inspect the cooling system for proper coolant level and condition.

      Is the Engine Coolant at the proper level and condition?

      Yes 

      • Go To  3

      No 

      • Repair the Engine Coolant level or condition problem. Inspect the vehicle for coolant leaks and repair if necessary. Fill the Engine Coolant to the proper level and ensure the proper condition.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to: POWERTRAIN VERIFICATION TEST .
  3. CHECK THE THERMOSTAT OPERATION 
    NOTE:

    For optimal test results, allow the vehicle to sit outside long enough to cool to ambient temperature in order to start the test with a totally cold soaked engine. With the scan tool, read the Engine Coolant Temperature degree value. If the engine was allowed to sit (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.

    1. Turn the ignition on.
    2. If engine coolant temperature is above 82°C (180°F), allow the engine to cool until it reaches at least 65°C (150°F) or cooler before continuing with this test.
    3. Start the engine.
    4. During engine warm-up monitor the Engine Coolant Temperature degree value on the scan tool. The temperature value change should be a smooth transition from start up to Thermostat opening temperature. Also monitor the actual coolant temperature with a digital thermometer at or near the ECT Sensor and Thermostat positions.
      NOTE:

      As the engine warms up to operating temperature, the actual coolant temperature (thermometer reading) and the scan tool Engine Coolant Temperature degree values should stay relatively close to each other. A discrepancy may indicate an inaccurate ECT Sensor signal to the PCM.

    5. As the engine warms to operating temperature, record the temperature at which the Thermostat opens.
    6. Using the appropriate Service Information, determine the proper opening temperature of the Thermostat.

      Did the Thermostat open at the proper temperature?

      Yes 

      • Go To  4

      No 

  4. CHECK THE RADIATOR FOR RESTRICTIONS AND FLOW 
    NOTE:

    The engine must be running and the Thermostat open to perform this test.

    1. Check and compare the temperatures at the inlet and outlet of the Radiator. Check for proper operation of the entire cooling system. Be certain to check for proper operation of the Radiator Cap. Check for proper flow through the Radiator and anything that can cause a lack of system pressure or lack of coolant flow in the system which include air in the cooling system, proper operation of the Water Pump and drive belt, restricted Radiator core, collapsed hose restricting flow, etc.
      NOTE:

      It is normal to observe a lower temperature on the outlet of the Radiator, however a very large difference could indicate a restriction in the Radiator. This condition can cause this DTC to set due to the position of the ETC Sensor in the coolant system. If necessary, compare the temperature difference with a similar vehicle.

      Was the difference in the temperature readings relatively larger than expected?

      Yes 

      • Check the cooling system and Radiator for proper flow and repair as necessary.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to: POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  5
  5. CHECK FOR HIGH RESISTANCE IN THE ECT SENSOR TEMP SIGNAL CIRCUIT 
    1. Turn the ignition off.
    2. Disconnect the ECT Sensor harness connector.
    3. Disconnect the PCM C2 harness connector.
      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 the GPEC Diagnostic Adaptor to perform the diagnosis.

    4. Connect the special tool # 10436, (GPEC Diagnostic Adapter) to the appropriate PCM connector.
      NOTE:

      The GPEC Diagnostic Adaptor can add up to 1.5 Ohms of resistance in the measurement of the circuit.

    5. Measure the resistance of the ECT Sensor Temp Signal circuit between the ECT Sensor harness connector and the GPEC Adaptor.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  6

      No 

      • Repair the ECT Sensor Temp Signal circuit for an open circuit or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to: POWERTRAIN VERIFICATION TEST .
  6. CHECK FOR HIGH RESISTANCE IN THE SENSOR GROUND CIRCUIT 
    1. Measure the resistance of the Sensor Ground circuit between the ECT Sensor harness connector and the GPEC Adaptor.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  7

      No 

      • Repair the Sensor Ground circuit for an open circuit or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to: POWERTRAIN VERIFICATION TEST .
  7. CHECK THE ABILITY OF THE PCM TO READ THE ECT SENSOR SIGNAL USING A JUMPER 
    1. Turn the ignition off.
    2. Reconnect the PCM C2 harness connector.
    3. Turn the ignition on.
    4. With the scan tool, read DTCs.
      NOTE:

      The P0118-ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT HIGH DTC should be active or pending with the connector unplugged.

    5. Connect a jumper between the ECT Sensor Temp Signal circuit and the Sensor Ground circuit at the ECT Sensor harness connector.
    6. With the scan tool, read DTCs.
      NOTE:

      The P0117-ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT LOW DTC should be active or pending with the jumper in place.

      Does the scan tool display as described above?

      Yes 

      No 

      • Go To  8
  8. CHECK RELATED PCM AND COMPONENT CONNECTIONS 
    1. Perform any Service Bulletins that apply.
    2. Disconnect all PCM harness connectors.
    3. Disconnect all related in-line harness connections (if equipped).
    4. Disconnect the related component harness connectors.
    5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
      • Proper connector installation.
      • Damaged connector locks.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Bent terminals.
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
      • Terminals that have been pushed back into the connector cavity.
      • Check for spread terminals and verify proper terminal tension.

      Repair any conditions that are found.

    6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    9. With the scan tool, erase DTCs.
    10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
    11. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      No 

      • The wiring or poor connection problem has been repaired.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to: POWERTRAIN VERIFICATION TEST .
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