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Home >> Jeep >> 2018 >> Grand Cherokee Laredo, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 5 (3.0L Diesel - DTCS P0001-00 To P01CC-00) >> DTC Troubleshooting >> P0090-00-Fuel Pressure 1 Control Circuit/Open >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FOR AN ACTIVE DTC 
    1. 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 THE (K646) FUEL PRESSURE REGULATOR CONTROL CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    GC0143521Courtesy of CHRYSLER GROUP, LLC
    1. Turn the ignition off.
    2. Disconnect the Fuel Pressure Regulator harness connector.
    3. Disconnect the PCM C2 harness connector.
    4. Measure the resistance of the (K646) Fuel Pressure Regulator Control circuit between the Fuel Pressure Regulator harness connector and the PCM C2 harness connector.

      Is the resistance below 5.0 Ohms?

      Yes 

      • Go To  3

      No 

      • Repair the (K646) Fuel Pressure Regulator Control circuit for an open or high resistance.
      • Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  3. CHECK THE (K369) FUEL PRESSURE REGULATOR RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    GC0143522Courtesy of CHRYSLER GROUP, LLC
    1. Measure the resistance of the (K369) Fuel Pressure Regulator Return circuit between the Fuel Pressure Regulator harness connector and the PCM C2 harness connector.

      Is the resistance below 5.0 Ohms?

      Yes 

      • Go To  4

      No 

      • Repair the (K369) Fuel Pressure Regulator Return circuit for an open or high resistance.
      • Perform the PCM VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  4. CHECK THE FUEL PRESSURE REGULATOR FOR PROPER OPERATION 
    1. Reconnect the Fuel Pressure Regulator harness connector.
    2. Reconnect the Powertrain Control Module C2 harness connector.
    3. Turn the ignition on.
    4. With the scan tool, erase DTCs.
    5. Turn the ignition off.
    6. Disconnect the Fuel Pressure Regulator harness connector.
    7. Connect a jumper between the (K646) Fuel Pressure Regulator Control circuit and ground.
    8. Turn the ignition on.
    9. With the scan tool, select View DTCs.
      NOTE:

      The scan tool should display a P0091-FUEL PRESSURE CONTROL CIRCUIT LOW DTC with the jumper in place.

      Did the scan tool display P0091-FUEL PRESSURE CONTROL CIRCUIT LOW DTC with the jumper in place?

      Yes 

      No 

      • Go To  5
  5. 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