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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Basic Diagnostic Procedures >> No-Start Diagnosis >> No-Start - Engine Cranks Okay (4.8L, 5.3L & 6.0L) >> Diagnostic Procedure

Diagnostic Procedure

  1. Perform DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C" & "K" SERIES TRUCKS article. After performing DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS, go to next step.
  2. Crank the engine for 15 seconds. Does the scan tool display any DTCs that failed this ignition? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C" & "K" SERIES TRUCKS article. If no, go to next step.
  3. Using scan tool, check the Body Control Module (BCM) for DTCs related to the Vehicle Theft Deterrent (VTD) system. Does the scan tool display any BCM VTD DTCs? If yes, perform DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT. If no, go to next step.
  4. Using scan tool, monitor the engine speed while cranking the engine. Is engine RPM indicated on the scan tool? If yes, go to next step. If no, see ELECTRONIC IGNITION SYSTEM DIAGNOSIS under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - TRUCKS - EXCEPT TRACKER article.
  5. Turn ignition switch to ON position. Using a test light connected to ground, probe both sides of fuses INJR A, INJR B and ECM I, located in the underhood electrical center. Does the test light illuminate on both sides of all 3 fuses? If yes, go to next step. If no, see IGNITION RELAY DIAGNOSIS under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - TRUCKS - EXCEPT TRACKER article.
  6. Using the scan tool, monitor the Engine Coolant Temperature (ECT) parameter. Is the ECT on the scan tool close to the actual engine temperature? If yes, go to next step. If no, see DTC P0118: ECT SENSOR CIRCUIT - HIGH VOLTAGE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C" & "K" SERIES TRUCKS article.
  7. Using the scan tool, enable the fuel pump. Does the fuel pump operate? If yes, go to next step. If no, see FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS under FUEL SYSTEMS (GASOLINE) in SYSTEM & COMPONENT TESTING - TRUCKS - EXCEPT TRACKER article.
  8. Turn ignition switch to OFF position. Release fuel pressure and install a fuel pressure gauge. See FUEL SYSTEM PRESSURE RELEASE (4.8L, 5.3L, 6.0L & 8.1L)  under BASIC FUEL SYSTEM CHECKS (GASOLINE). The fuel pump operates for about 2 seconds when the ignition switch is turned to the ON position. The fuel pressure must be observed when the fuel pump is operating. Turn ignition switch to ON position. Observe the fuel pressure while the fuel pump is operating. Is the fuel pressure 55-62 psi (379-427 kPa)? If yes, go to next step. If no, diagnose fuel system. See FUEL SYSTEM PRESSURE TEST under BASIC FUEL SYSTEM CHECKS (GASOLINE).
  9. Perform the following checks:
    • Check air duct between MAF sensor and throttle body for air leaks.
    • Using scan tool, ensure throttle angle is at zero percent with throttle closed. If throttle angle is not as specified, diagnose using appropriate diagnostic procedure for TP sensor DTCs. See DTC P0121: TP SENSOR PERFORMANCE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C" & "K" SERIES TRUCKS article.
    • A malfunctioning Mass Airflow (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 OK, replace the MAF sensor. See MASS AIRFLOW SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - SIERRA & SILVERADO article.
    • Check for fouled spark plugs. If fouled, determine cause and repair as necessary.
    • Check for possible engine mechanical failure causing a no-start condition, such as timing chain or low compression.
    • Compare the MAP/BARO parameters to another vehicle. The parameter values should be close to each other.

    Did you find and correct the condition? If yes, go to next step. If no, see HARD START under SYMPTOMS (GASOLINE) in TROUBLE SHOOTING - NO CODES - TRUCKS article.

  10. Using scan tool, clear DTCs. Attempt to start engine. Does engine start and continue to run? If yes, go to next step. If no, go to step  2.
  11. Start and idle engine until normal operating temperature is reached. Using scan tool, check for DTCs. If any DTCs are set, diagnose DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C" & "K" SERIES TRUCKS article. If no DTCs are set, go to next step.
  12. Using scan tool, select CAPTURE INFO and REVIEW INFO functions. If any DTCs are set that have not been diagnosed, diagnose DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C" & "K" SERIES TRUCKS article. If no DTCs are set, system is okay.
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