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Home >> Jeep >> 2023 >> Grand Cherokee Altitude, AWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 39 (2.0L - DTCS P0004 To P0087) >> DTC Troubleshooting >> P0004 Fuel Quantity Control Circuit High >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FOR ANY SERVICE BULLETINS OR PCM SOFTWARE UPDATES 
    1. Check for any applicable Service Bulletins or Flash updates related to the DTC.

      Are there any applicable Service Bulletins or Flash updates?

      Yes 

      No 

      • Go To  2
  2. READ AND RECORD DTCS AND ENVIRONMENTAL DATA - ERASE DTCS AND CHECK FOR THE DTC TO RETURN 
    1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
    2. For future reference, with the scan tool, 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. Using the When Monitored and Set Conditions above and recorded data, operate the vehicle in the conditions that set the DTC.
    7. With the scan tool, read DTCs.

    Did the DTC return?

    Yes 

    • Go To  3

    No 

  3. CHECK THE FUEL QUANTITY SOLENOID CONNECTOR AND TERMINALS 
    1. Turn the ignition off.
    2. Check the FQS harness connector for proper connection at the High Pressure Fuel Pump Assembly.
    3. Verify that the connector is completely plugged in and properly locked prior to disconnecting.
    4. Disconnect the FQS harness connector and check for pushed out, damaged or spread terminals.

      Were any issues found with the connector or terminals?

      Yes 

      • Repair the damaged terminal or properly connect and lock the FQS harness connector and retest for DTCs.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  4
  4. ISOLATE AND CHECK THE FUEL QUANTITY SOLENOID (N17) HIGH SIDE CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT AT THE PCM HARNESS CONNECTOR 
    1. The ignition must be off when performing a resistance check to find a short between circuits.
    2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested. At this time leave all in-line connectors connected. Note:  Use the appropriate SYSTEM WIRING DIAGRAM as a guide to follow the path of the circuit.
    3. Connect one lead of the DVOM to the circuit being tested at the ECU harness connector.
    4. With the other lead of the DVOM probe all other circuits at the ECU 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 conduct the diagnosis.

    1. If it is necessary to probe a terminal at a PCM harness connector, connect the special tool # 10436, (GPEC Diagnostic Adapter) to the appropriate PCM harness connector.
      NOTE:

      With the circuit isolated there should be no continuity between the circuit being tested and any other circuit.

      Is there continuity between the circuit being tested and any other circuit?

      Yes 

      • Repair the short between the circuits that have continuity. Use the appropriate SYSTEM WIRING DIAGRAM as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  5
  5. ISOLATE AND CHECK THE FUEL QUANTITY SOLENOID (N18) LOW SIDE CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT AT THE PCM HARNESS CONNECTOR 
    1. The ignition must be off when performing a resistance check to find a short between circuits.
    2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and every component harness connector containing the circuit being tested. At this time leave all in-line connectors connected. Note:  Use the appropriate SYSTEM WIRING DIAGRAM as a guide to follow the path of the circuit.
    3. Connect one lead of the DVOM to the circuit being tested at the ECU harness connector.
    4. With the other lead of the DVOM probe all other circuits at the ECU 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 conduct the diagnosis.

    1. If it is necessary to probe a terminal at a PCM harness connector, connect the special tool # 10436, (GPEC Diagnostic Adapter) to the appropriate PCM harness connector.
      NOTE:

      With the circuit isolated there should be no continuity between the circuit being tested and any other circuit.

      Is there continuity between the circuit being tested and any other circuit?

      Yes 

      • Repair the short between the circuits that have continuity. Use the appropriate SYSTEM WIRING DIAGRAM as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  6
  6. DISCONNECT THE FUEL QUANTITY SOLENOID SENSOR HARNESS CONNECTOR AND VERIFY THE ABILITY OF THE PCM TO READ THE CONTROL CIRCUIT OPEN DTC 
    1. The Electronic Control Unit (ECU) harness connectors must be connected to the ECU during this test step.
    2. With the ignition in the off position, disconnect the sensor harness connector.
    3. Turn the ignition on.
    4. With the scan tool, read DTCs.

    Does the scan tool display the FUEL QUANTITY CONTROL CIRCUIT OPEN DTC with the connector disconnected?

    Yes 

    • Replace the faulty solenoid in accordance with the Service Information.
    • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

    No 

    • Go To  7
  7. CHECK RELATED PCM AND COMPONENT CONNECTIONS 
    1. Carry out 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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