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Home >> Jeep >> 2022 >> Gladiator Mojave, Part Time T/Case Control, Standard Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 18 (3.0L Diesel - DTCS P0274-00 To P0381-00) >> DTC Troubleshooting >> P0300-00-Multiple Cylinder Misfire >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. 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, 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 75.0 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  2

      No 

      • Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT DTC .
  2. CHECK FOR OTHER DTCS 
    1. Refer to the recorded DTCs.

      Are there any active component or circuit DTCs active or pending?

      Yes 

      No 

      • Go To  3
  3. DIAGNOSTIC INSPECTION 
    NOTE:

    Anything that affects the speed of the crankshaft can cause this DTC to set. When a misfire is detected, the PCM will shut down the injector control circuit for the misfiring cylinder. Misfire may occur and may not be caused by component failure. Any of the following conditions can cause a misfire.

    1. Inspect the engine for any of the following conditions:
      • Worn serpentine belt
      • Misalignment or binding water pump, P/S pump or A/C compressor pulleys
      • Improper CKP, CMP, or MAP Sensor mounting.
      • Poor connector/terminal to component connection for CKP sensor, CMP sensor, MAP sensor, throttle body, fuel injector, etc.
      • Corroded PCM power or ground circuits.
      • Vacuum leaks.
      • Restriction in the air induction or exhaust system.
      • Internal engine component malfunction.
      • Insufficient fuel
      • Low quality fuel
      • Manual transmission bog
      • Towing overload

      Were any problems found?

      Yes 

      No 

      • Go To  4
  4. CHECKING THE FUEL DELIVERY SYSTEM 
    1. Perform the diagnostic procedures for FUEL PRESSURE LEAK DOWN and FUEL DELIVERY SYSTEM OUTPUT - FLOW TEST.

      Were any problems found?

      Yes 

      No 

      • Go To  5
  5. CHECKING THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION 
    1. Perform the diagnostic procedure for CHECKING THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION.

      Were any problems found?

      Yes 

      No 

      • Go To  6
  6. CHECKING THE OXYGEN SENSOR OPERATION 
    1. Perform the diagnostic procedure for CHECKING THE OXYGEN SENSOR OPERATION.

      Were any problems found?

      Yes 

      No 

      • Go To  7
  7. CHECKING THE ENGINE MECHANICAL SYSTEM 
    1. Perform the diagnostic procedure for CHECKING THE ENGINE MECHANICAL SYSTEM.

      Were any problems found?

      Yes 

      No 

      • Go To 8
  8. 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 

      • Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to 3.0L, POWERTRAIN VERIFICATION TEST .

      No