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Home >> Isuzu >> 2003 >> Axiom Base, RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Diagnostic Procedures >> No Start Diagnosis >> Engine Cranks But Does Not Run (Ascender 5.3L) >> Testing Procedure

Testing Procedure

  1. Perform the DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - ASCENDER 5.3L article. Go to next step.
  2. Crank the engine for 15 seconds. If the scan tool displays DTCs that failed this ignition, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - ASCENDER 5.3L article. If no codes are present, go to next step.
  3. Does the scan tool display any Body Control Module (BCM) Vehicle Theft Deterrent (VTD) DTCs? If DTCs are present, see DIAGNOSTIC SYSTEM CHECK - THEFT DETERRENT in appropriate THEFT DETERRENT article in ACCESSORIES & EQUIPMENT. If no codes are present, go to next step.
  4. Observe the engine speed parameter with a scan tool, while cranking the engine. Of the engine RPM is indicated on the scan tool, go to next step. If the RPM is not indicated, see IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING article.
  5. Turn ignition on, with engine off. Probe both sides of the PCM 1 fuse located in the underhood electrical center with a test lamp connected to a good ground. If the test lamp illuminates on at least one side of the fuse, go to the next step. If the test lamp does not illuminate, see IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING article.
  6. Monitor the ignition 1 signal parameter with a scan tool. If the ignition 1 signal is battery voltage, go to next step. If the ignition 1 signal is not battery voltage, go to step  11 .
  7. Command the fuel pump ON with a scan tool. If the fuel pump operates, go to next step. If the fuel pump does not operate, see FUEL SYSTEMS in SYSTEM & COMPONENT TESTING article.
    8. NOTE: The fuel pump operates for about 2 seconds when the ignition is turned ON. The fuel pressure must be observed when the fuel pump is operating.
  8. Turn ignition off. Install a fuel pressure gauge. See FUEL SYSTEM DIAGNOSIS  . Turn ignition on, with engine off. Observe the fuel pressure while the fuel pump is operating. If the fuel pressure is within the specified range of 55-62 psi (385-425 kPa), go to next step. If the fuel pressure is not within the specified range, go to FUEL SYSTEM DIAGNOSIS  .
  9. Inspect for the following conditions:
    • The engine coolant temperature sensor is not close to the actual engine temperature. See DTC P0125: EXCESSIVE TIME TO ENTER CLOSED LOOP .
    • The duct work between the MAF sensor and the throttle body for air leaks.
    • A restricted exhaust system.
    • A malfunctioning MAF sensor may cause a no start or a stall after a start. If you suspect this, disconnect the MAF sensor. The PCM will default to the speed density in order to calculate the engine load and the intake air flow. If disconnecting the MAF sensor corrects the condition and the connections are okay see DTC P0102: MAF SENSOR CIRCUIT - LOW FREQUENCY .
    • The spark plugs for being gas fouled.
    • An engine mechanical failure that causes an engine not to start such as timing chain, or low compression.
    • Compare the MAP/BARO parameters to another vehicle. The parameter values should be close to each other.
    When all checks are complete go to step  13 .
  10. Test the ignition 1 voltage circuits that are supplied by the PCM 1 fuse for an open or for a short to ground. Replace the fuse if necessary. If the condition was found and repaired go to step  13 . If the condition was not found and repaired, go to next step.
  11. Inspect for poor connections at the harness connector of the PCM. If the condition was found and repaired, go to  13 . If the condition was not found and repaired, go to next step.
  12. Replace the PCM. After replacing PCM, go to next step.
  13. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Attempt to start the engine. If the engine starts and continues to run, go to next step. If the engine does not start and continue to run, go to step  2 .
  14. Allow the engine to reach operating temperature. Observe the DTC information with a scan tool. If there are any DTCs that have not been diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - ASCENDER 5.3L article. If there are no codes the system is okay.
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