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Home › Cadillac › 2003 › Seville SLS › Repair and Diagnosis › Engine Performance › System › Engine Controls - Basic Diagnostic Procedures › No-Start Diagnosis › Engine Cranks But Does Not Run › Diagnostic Procedure

Diagnostic Procedure

  1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article.
  2. Turn ignition ON, with engine OFF. Using scan tool, observe DTC information. Does the scan tool display DTC P0230, P0335, P0340, P0385, P0403, P0404, P0601, P0602, P1404, P0603, P0604, P1621, P1630, P1631 or P2610? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article. If no DTC(s) are set, go to next step.
  3. Inspect the fuse that supplies ignition voltage to the ignition coil cassette. Is fuse open? If yes, go to ELECTRONIC IGNITION SYSTEM DIAGNOSIS  under IGNITION SYSTEMS. If no, go to next step.
  4. Using scan tool, command fuel pump ON. Does fuel pump turn on? If yes, go to next step. If no, go to FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS  under FUEL SYSTEMS.
  5. Turn ignition OFF. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition ON, with engine OFF. Using scan tool, command the fuel pump ON. Is fuel pressure within 41-47 psi (284-325 kPa) while fuel pump is operating? If yes, go to next step. If no, go to FUEL SYSTEM DIAGNOSIS  under FUEL SYSTEMS.
  6. Check the following:
    • Check for collapsed air intake duct.
    • Check for restricted air filter element.
    • Check spark plugs for being gas or coolant fouled. If spark plugs are fouled, determine cause of condition.
    • Check engine mechanical condition, such as worn timing chain and gears, low compression, etc.
    • Restricted exhaust system.
    • Faulty Manifold Absolute Pressure (MAP) sensor. See DTC P0106: MAP SYSTEM PERFORMANCE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article.
    • Faulty Engine Coolant Temperature (ECT) sensor. See ENGINE COOLANT TEMPERATURE SENSOR under SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 4.6L DEVILLE & SEVILLE article.

    If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article.

  7. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, go to step  2.
  8. Allow engine to idle. Ensure engine is at normal operating range. Using scan tool, observe DTC information. If any DTCs are set, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article. If scan tool does not display any DTCs, system is okay.
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