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Home >> Jeep >> 2018 >> Compass Trailhawk >> Repair and Diagnosis >> Engine Performance >> System >> 2.4L - DTCS P152E To P257E >> DTC Troubleshooting >> P2181-Cooling System Performance >> Diagnostic Test
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Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    NOTE:

    Extremely cold ambient temperatures may cause this DTC to set.

    1. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
    2. With the scan tool, read DTCs and record on the repair order.

      Is the DTC active or pending?

      Yes 

      No 

      • Go To  2
  2. CHECK FOR OTHER DTCS 
    1. Refer to the recorded DTCs.

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

      Yes 

      • Perform the applicable diagnostic procedure(s). Refer to DTC INDEX .

      No 

      • Go To  3
  3. CHECK FOR LOW ENGINE COOLANT LEVEL 
    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.

      Were any problems found?

      Yes 

      • Inspect the vehicle for a coolant leak. Repair as necessary in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  4
  4. CHECK COOLING SYSTEM OPERATION FOR POOR FLOW OR IMPROPER WATER PUMP OPERATION 
    1. Check the overall cooling system for any problems such as poor flow due to a restrictions or possible faulty water pump operation. Refer to DIAGNOSIS AND TESTING .

      Were any problems found?

      Yes 

      No 

      • Go To  5
  5. CHECK THE THERMOSTAT OPERATION 
    1. Turn the ignition on.
      NOTE:

      Allow the engine to cool to ambient temperature before proceeding with this test.

    2. Using the appropriate Service Information, determine the proper opening temperature of the thermostat.
    3. With a scan tool, read the ECT Sensor value. If the engine was allowed to cool completely, the value should be approximately equal to the ambient temperature.
    4. Start the engine and allow it to reach operating temperature while monitoring the ECT Sensor value. The sensor value change should be a smooth transition from start up to normal operating temperature. 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 coolant temperature value on the scan tool should be relatively close. The thermostat should not open until the engine reaches the temperature specified in the Service Information.

      Does the thermostat open at the temperature specified in the Service Information?

      Yes 

      • Go To  6

      No 

      • Replace the Thermostat in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  6. CHECK THE (K2) ECT SENSOR SIGNAL CIRCUIT FOR AN/HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the Engine Coolant Temperature Sensor harness connector.
    3. Disconnect the Powertrain Control Module (PCM) C2 harness connector.
    4. Measure the resistance of the (K2) ECT Sensor Signal circuit between the Engine Coolant Temperature Sensor harness connector and the PCM C2 harness connector.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  7

      No 

      • Repair the (K2) ECT Sensor Signal circuit for an open circuit or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  7. CHECK THE (K900) SENSOR GROUND CIRCUIT FOR AN/HIGH RESISTANCE 
    1. Measure the resistance of the (K900) Sensor Ground 1 circuit between the Engine Coolant Temperature Sensor harness connector and the PCM C2 harness connector.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  8

      No 

      • Repair the (K900) Sensor Ground circuit for an open circuit or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  8. 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. Connect a jumper wire between the (K900) Sensor Ground circuit and the (K2) ECT Sensor Signal circuit in the Engine Coolant Temperature Sensor harness connector.
    4. Turn the ignition on.
    5. With the scan tool, read the Engine Coolant Temperature Sensor signal voltage.

      Is the voltage below 0.1 volts with the jumper wire in place?

      Yes 

      • Replace the Engine Coolant Temperature Sensor in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  9
  9. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all PCM harness connectors.
    2. Disconnect all related in-line harness connections (if equipped).
    3. Disconnect the related component harness connectors.
    4. 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.

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