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Home >> Chrysler >> 2018 >> Pacifica L, Gas >> Repair and Diagnosis >> Engine Performance >> System >> 3.6L - DTCS U0109 To U1504 >> DTC Troubleshooting >> U0109-Lost Communication With Fuel Pump Control Module >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    1. Turn the ignition on, engine not running.
    2. With the scan tool, read DTCs and record on the repair order.

      Is the DTC active or pending?

      Yes 

      • Go To  2

      No 

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

      Are there any Fuel Pump Relay Control circuit DTCs present?

      Yes 

      No 

      • Go To  3
  3. CHECK THE (N1) FUEL PUMP CONTROL OUTPUT CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the FPCM harness connector.
    3. Turn the ignition on.
    4. Measure the voltage on the (N1) Fuel Pump Control Output circuit at the FPCM harness connector.

      Is the voltage approximately equal to Battery voltage?

      Yes 

      • Go To  4

      No 

      • Repair the (N1) Fuel Pump Control Output circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  4. CHECK THE (N12) FPCM PWM FEEDBACK CIRCUIT FOR A SHORT TO GROUND 
    1. Turn the ignition off.
    2. Disconnect the FPCM harness connector.
    3. Disconnect the PCM C1 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. Check for continuity between ground and the (N12) FPCM PWM Feedback circuit at the FPCM harness connector.

      Is there continuity between ground and the (N12) FPCM PWM Feedback circuit?

      Yes 

      • Repair the (N12) FPCM PWM Feedback circuit for a short to ground.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  5
  5. CHECK THE (N12) FPCM PWM FEEDBACK CIRCUIT FOR A SHORT TO ANOTHER VOLTAGE SUPPLY 
    1. Check for continuity between the (N12) FPCM PWM Feedback circuit and all other circuits at the PCM C1 harness connector.

      Is there continuity between the (N12) FPCM PWM Feedback circuit and any other circuits at the PCM C1 harness connector ?

      Yes 

      • Repair the (N12) FPCM PWM Feedback circuit for a short to the circuit that showed continuity.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  6
  6. CHECK THE (N12) FPCM PWM FEEDBACK CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Measure the resistance of the (N12) FPCM PWM Feedback circuit between the FPCM harness connector and the PCM C1 harness connector.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  7

      No 

      • Repair the (N12) FPCM PWM Feedback circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  7. CHECK THE (Z921) GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Measure the resistance between ground and the (Z921) Ground circuit at the FPCM harness connector.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  8

      No 

      • Repair the (Z921) Ground circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  8. REPLACE THE FUEL PUMP CONTROL MODULE AND RETEST FOR DTC 
    1. Check the FPCM wiring and connector for terminals that look corroded or black from a poor connection. Repair any connection issues if found, reconnect all connectors and retest the system before replacing the Fuel Pump Control Module. If no problems were found with the wiring and connector, replace the Fuel Pump Control Module in accordance with the Service Information.
    2. Start the engine and allow it to idle until it reaches normal operating temperature.
    3. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go To  9

      No 

      • Replacing the Fuel Pump Control Module repaired the fault.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  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 

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