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Home >> Chevrolet >> 2000 >> Blazer 4D Utility, RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - 4.3L >> Diagnostic Tests >> DTC P0102: Mass Airflow Sensor Circuit - Low Frequency >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Install scan tool. Start engine. With engine at idle, monitor MAF sensor display on scan tool. If MAF display is less than 2 gm/s, go to step  4. If MAF display is not less than 2 gm/s, go to next step.
  3. Turn ignition on, engine off. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC for DTC P0102. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see DIAGNOSTIC AIDS .
  4. Check MAF fuse. If fuse is open, go to step  11. If fuse is okay, go to next step.
  5. Check for the following conditions:
    • Objects blocking MAF sensor inlet screen.
    • Intake manifold vacuum leaks.
    • Vacuum leaks at throttle body.
    • Vacuum leaks at EGR valve flange and pipes.
    • Crankcase ventilation valve faulty, missing or incorrectly installed.

    Repair as necessary. After repairs, go to step  17. If no problem is found, go to next step.

  6. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on, engine off. Using DVOM, check voltage between ground and signal circuit at MAF sensor harness connector. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step  10.
  7. Connect test light between MAF ignition feed and ground circuits at MAF sensor harness connector. If test light illuminates, go to step  9. If test light does not illuminate, go to next step.
  8. Connect a test light between ignition feed circuit at MAF sensor harness connector and battery ground. If test light illuminates, go to step  12. If test light does not illuminate, go to step  13.
  9. Check for poor connection at MAF sensor. Repair as necessary. After repairs, go to step  17. If connection is okay, go to step  14.
  10. Check for open, short to ground, short to MAF ground circuit or short to voltage in MAF signal circuit between MAF sensor and VCM. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to step  15.
  11. Locate and repair short to ground in MAF sensor ignition voltage circuit. After repairs, go to step  17.
  12. Locate and repair open in MAF sensor ground circuit to MAF sensor. After repairs, go to step  17.
  13. Locate and repair open in ignition feed circuit to MAF sensor. After repairs, go to step  17.
  14. Replace MAF sensor. After replacing sensor, go to step  17.
  15. Check for poor connections at VCM. Repair as necessary. After repairs, go to step  17. If connections are okay, go to next step.
  16. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
  17. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, and then enter this DTC. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step  2.
  18. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.
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