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Home >> Jeep >> 2021 >> Cherokee Trailhawk >> Repair and Diagnosis >> Engine Performance >> System >> 3.2L - DTCS P054C To P1129 >> DTC Troubleshooting >> P0627-Fuel Pump Control Circuit Open >> Diagnostic Test
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Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    NOTE:

    If there are any ASD/Main Relay or system voltage DTCs present, diagnose those DTCs before proceeding with this test procedure.

    1. Turn the ignition on.
    2. With the scan tool, read DTCs. Copy DTC and Freeze Frame information and erase DTCs.
      NOTE:

      Active or pending DTCs may not allow Fuel Pump actuation, ensure all DTCs are cleared before proceeding with this test procedure.

    3. Cycle the ignition off and back on for 15 seconds.
    4. Attempt to start or crank the engine.
    5. With the scan tool, read DTCs and record on the repair order.

      Did the DTC return?

      Yes 

      • Go To  2

      No 

  2. CHECK THE (K31) FUEL PUMP CONTROL CIRCUIT FOR ANOTHER VOLTAGE SUPPLY 
    1. Turn the ignition off.
    2. Disconnect the PCM C1 harness connector.
    3. Disconnect the PDC 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. Check for continuity between the (K31) Fuel Pump Control circuit and all other 5.0 volt and 12.0 volt supply circuits at the GPEC Adaptor?

      Is there continuity between the (K31) Fuel Pump Control circuit and any other 5.0 volt and 12.0 volt supply circuit?

      Yes 

      • Repair the (K31) Fuel Pump Control circuit for a short to the circuit that showed continuity.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  3
  3. CHECK THE (K31) FUEL PUMP CONTROL CIRCUIT FOR A SHORT TO GROUND 
    1. Check for continuity between ground and the (K31) Fuel Pump Control circuit at the GPEC Adaptor.

      Is there continuity between ground and the (K31) Fuel Pump Control circuit?

      Yes 

      • Repair the (K31) Fuel Pump Control circuit for a short to ground.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  4
  4. CHECK THE (K31) FUEL PUMP RELAY CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Measure the resistance of the (K31) Fuel Pump Control circuit between the PDC connector and the GPEC Adaptor.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  5

      No 

      • Repair the (K31) Fuel Pump Relay Control circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  5. CHECK THE POWER DISTRIBUTION CENTER 
    1. Reconnect the PDC harness connector.
    2. Reconnect the PCM C1 harness connector with the GPEC Adaptor connected in-line.
    3. Turn the ignition on, engine not running or cranking.
    4. Measure the voltage on the (K31) Fuel Pump Relay Control circuit at the GPEC Adaptor.
      NOTE:

      Allow the Fuel Pump to time out before measuring the voltage on the circuit.

      NOTE:

      There should be Battery voltage present with the Fuel Pump Relay Control circuit not being grounded by the PCM.

      Is Battery voltage present?

      Yes 

      • Go To  6

      No 

      • Check the fuses in the PDC. If a fuse is blown, replace it and retest the system. If all of the fuses are good, replace the Power Distribution Center in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  6. 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.

      Is the DTC active or pending?

      Yes 

      No 

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