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Home >> Jeep >> 2014 >> Grand Cherokee Laredo, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (DRIVEABILITY - Diesel - Non-DTC Based Diagnostics) >> Diagnosis And Testing >> Engine Cranks But Will Not Start >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. PCM CODES PRESENT 
    NOTE:

    The PCM must have proper power and ground connections for the following tests to be valid. Refer to CHECKING THE PCM POWER AND GROUND CIRCUITS .

    1. Turn the ignition on.
    2. Using the scan tool, read the PCM DTCs.

      Does the scan tool display any PCM DTCs?

      Yes 

      • Refer to DTC INDEX and perform the appropriate diagnostic procedure.

      No 

      • Go To  2
  2. VEHICLE SECURITY CODES PRESENT 
    1. With the scan tool, read the WIN DTCs.

      Does the scan tool display any WIN DTCs?

      Yes 

      No 

      • Go To  3
  3. CHECK FOR INTAKE SYSTEM LEAKS OR RESTRICTIONS 
    1. Turn the ignition off.
    2. Make sure vehicle has adequate fuel supply in fuel tank.
    3. Carefully inspect all air intake and Turbocharger related hoses/tubes and connections for leaks.
    4. Inspect the air filter for excessive dirt, soiling or other problems that may cause restricted air flow.

      Were any problems found?

      Yes 

      • Repair or replace as necessary.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .

      No 

      • Go To  4
  4. ECT SENSOR 
    1. Using a temperature probe, check the vehicle temperature near the ECT Sensor.
    2. Turn the ignition on.
    3. With the scan tool in Sensors, read the ECT Sensor temperature.
    4. Compare the temperature probe reading with the scan tool reading.

      Are the two readings within 10°C of each other?

      Yes 

      • Go To  5

      No 

      • Repair as necessary.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .
  5. GLOW PLUGS 
    NOTE:

    Prior to performing this test, be sure to check the Glow Plug Relay operation.

    1. Check the Glow Plugs for proper operation.

      Are the Glow Plugs operating properly?

      Yes 

      • Go To  6

      No 

      • Repair as necessary.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .
  6. FUEL SYSTEM RESTRICTION 
    1. Inspect the fuel system lines for restrictions, leaks or other problems.

      Is there any evidence of problems?

      Yes 

      • Repair as necessary.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .

      No 

      • Go To  7
  7. FUEL CONTAMINATION 
    1. Inspect the fuel supply for contamination.

      Is the fuel contaminated?

      Yes 

      • Drain and replace the contaminated fuel in the system.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .

      No 

      • Go To  8
  8. CHECK FUEL PRESSURE AT ENGINE CRANKING 
    1. Using the scan tool, read the Fuel Pressure Sensor signal while cranking the engine.

      Does the Fuel Pressure Sensor signal increase to above 3500 psi (240 bar) within a few seconds after engine cranking begins?

      Yes 

      • Go To  9

      No 

  9. CRACKED OR BROKEN FLEX PLATE 
    1. Use the service information to gain access to and inspect for a broken or cracked flex plate.

      Were any problems found?

      Yes 

      • Repair as necessary.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .

      No 

      • Go To  10
  10. ENGINE DRIVE CHAINS 
    1. Refer to the service information and make sure the Engine Drive Chain is installed correctly and the camshaft and crankshaft gears are timed correctly.

      Were any problems found?

      Yes 

      • Repair as necessary.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .

      No 

      • Replace and program the Powertrain Control Module in accordance with the service information.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .