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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 2A) - DTCS P1239 To P1495 >> DTC Troubleshooting >> P1404-EGR Close Position Performance >> Diagnostic Test

Diagnostic Test

  1. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR AN ACTIVE CONDITION 
    1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    2. For future reference, run and save a vehicle Scan Report and all related recorded data.
    3. With the scan tool, erase all DTCs.
    4. Turn the ignition off for a minimum of 10.0 seconds.
    5. Turn the ignition on.
    6. With scan tool, read and record the 'EGR Valve Zero Reference Position' or 'EHBVC EE ZERO REF'  value.
      NOTE:

      This fault can set due to temporary carbon buildup interfering with the disc closing completely. Many times this DTC is stored because the carbon cleaned itself from the valve and disc allowing the valve to return to the full closed position. Reading the EGR position signal voltage value in the scan tool data display can determine if the valve is sticking or stuck open. As the valve opens, the position sensor signal voltage increases. In the fully closed position the EGR Valve position voltage signal should read approximately 0.5 - 0.52 volts in the scan tool data display.

      Is the Zero Reference Position voltage above 0.640 volts?

      Yes 

      • Go To  2

      No 

      • The condition is not present at this time. There may have been carbon build-up that is cleared. The other possible scenario is possible intermittent connection or resistance in the EGR position sensor circuitry causing an intermittent false voltage feedback reading. Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
  2. CHECK FOR OTHER DTCS 
    1. Refer to the recorded DTCs.

      Are there any EGR Valve Position Sensor or EGR Valve Control DTCs active or pending?

      Yes 

      No 

      • Go To  3
  3. VEHICLE ROAD TEST 
    NOTE:

    Perform the following, while maintaining connection with scan tool.

    1. Start the engine and allow vehicle to idle or drive vehicle normally to bring coolant temperature to normal operating range above 71°C (160°F).
    2. Drive vehicle for at least 3 miles to allow the EGR Valve to open. Turn off ESS so the engine does not shut off at stops. At takeoffs, use moderate acceleration but avoid full throttle accelerations. Note:  The EGR System does not operate at idle. It typically operates during constant speed driving.
    3. Park the vehicle and shut the engine off for ten seconds.
      NOTE:

      This will allow the EGR cleaning routine to run at engine shutdown. This can be heard as the EGR Valve will make 5 full stroke actuations.

    4. Turn the ignition on.
    5. With scan tool, read the Zero Reference Position  and record value.

      Did Zero Reference Position drop by 0.12 volts or return back to the normal closed position?

      Yes 

      • The EGR cleaning routine cleared the carbon build-up after test driving the vehicle to operating temperature.

      No 

      • Go To  4
  4. CHECK THE EGR POSITION SENSOR CIRCUITS FOR HIGH RESISTANCE 
    NOTE:

    It is possible for resistance in the position sensor circuits can cause the voltage reading to drift out of range without setting a position sensor signal fault.

    1. Turn the ignition off.
    2. Disconnect the EGR Valve 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, Adapter, GPEC Diagnostic)
    5. Measure the resistance of the:
      • EGR Valve (K683) Position Signal circuit between the EGR Valve harness connector and the GPEC Adaptor.
      • EGR Valve (K900) Sensor Ground circuit between the EGR Valve harness connector and the GPEC Adaptor.

      Is the resistance below 3.0 Ohms for both measurements?

      Yes 

      • Go To  5

      No 

  5. CHECK THE VEHICLE'S REPAIR HISTORY 
    1. Check the history of the vehicle for previous EGR Valve performance related DTCs within the past 90 days.

      Does the repair history show that the vehicle was in dealership for a EGR Valve performance fault within the past 90 days?

      Yes, and the EGR Valve was cleaned during the previous visit: 

      • Verify that the connector is completely connected. Check the connector terminals for any pushed out, corroded or spread terminals causing a poor or intermittent connection. If the connector is good, replace the EGR Valve Assembly in accordance with the Service Information. The EGR VALVE REPLACED routine must be performed after replacing or cleaning the EGR Valve to reset the zero learn position. Failure to do so will cause a false failure and the P1404 DTC to set. With the scan tool, perform the EGR VALVE REPLACED routine.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      Yes, and the EGR Valve was replaced during the previous visit 

      • Verify that the connector is completely connected. Check the connector terminals for any pushed out, corroded or spread terminals causing a poor or intermittent connection. If the connector is good, Clean the valve by running Mopar Combustion Chamber cleaner through the engine. The EGR VALVE REPLACED routine must be performed after replacing or cleaning the EGR Valve to reset the zero learn position. Failure to do so will cause a false failure and the P1404 DTC to set. With the scan tool, perform the EGR VALVE REPLACED routine. Test drive the vehicle and verify the DTC does not return. If the fault does not return, check the engine for any fuel or air handling issues that can cause excessive soot or carbon buildup in the engine.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  6
  6. CHECK THE EGR VALVE FOR CARBON OR SOOT BUILD UP 
    1. Turn the ignition off.
    2. Remove the EGR Valve Assembly.
    3. Clean the carbon from the EGR Valve disc and seat. The EGR VALVE REPLACED routine must be performed after replacing or cleaning the EGR Valve to reset the zero learn position. Failure to do so will cause a false failure and the P1404 DTC to set. With the scan tool, perform the EGR VALVE REPLACED routine.
    4. Re-install the EGR Valve.
    5. Reconnect the EGR Valve and PCM C2 harness connectors.
    6. Start the engine and allow it to idle.
    7. With scan tool, read the Zero Reference Position  and record value.

      Did Zero Reference Position return back to the normal closed position voltage (0.50 - 0.52 volts)?

      Yes 

      No 

      • Replace the EGR Valve Assembly in accordance with the Service Information. The EGR VALVE REPLACED routine must be performed after replacing or cleaning the EGR Valve to reset the zero learn position. Failure to do so will cause a false failure and the P1404 DTC to set. With the scan tool, perform the EGR VALVE REPLACED routine.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
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