Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Isuzu >> 2000 >> Hombre S, 4.3 W >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 4.3L >> Diagnostic Trouble Code Identification >> DTC P0101: MAF Sensor System Performance >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostics II (OBD-II) System Check. See SELF-DIAGNOSTICS - INTRODUCTION article. Retrieve and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
  2. Turn ignition on, with engine off. Using Tech 2 scan tool, monitor MAP sensor display. If displayed MAP sensor value greater than 100 kPa, go to next step. If MAP sensor display is less than 100 kPa, go to step  20.
  3. Remove MAP sensor from intake manifold, leaving harness connected. Connect hand-held vacuum pump (J23738-A) to MAP sensor. While observing MAP sensor value on scan tool, slowly apply vacuum until 20 in. Hg is obtained. Value drop of 3-4 kPa should occur. If value change is smooth, without erratic readings, go to next step. If value change is not as described, go to step  20.
    NOTE: Any MAP sensor DTCs stored must be corrected before proceeding.
  4. Apply 20 in. Hg vacuum to MAP sensor. If scan tool MAP sensor value is 34 kPa or less, go to next step. If scan tool MAP sensor value is greater than 34 kPa, go to step  20.
  5. Disconnect vacuum source from MAP sensor. If scan tool MAP sensor value returns to 100 kPa, go to next step. If scan tool MAP sensor value does not return to 100 kPa, go to step  20.
  6. Turn ignition on, with engine off. Using 2 scan tool, review and record FAILURE RECORDS data. Operate vehicle within failure records conditions. Monitor SPECIFIC DTC information for DTC P0101. If scan tool indicates DTC P0101 failed during this ignition cycle, go to next step. If scan tool does not indicate DTC P0101 failed during this ignition cycle, go to DIAGNOSTIC AIDS .
  7. Check for vacuum leaks at the following:
    • Intake manifold.
    • Throttle body.
    • EGR valve flange and pipes.
    • MAP sensor seal.
    • EVAP canister purge valve seal.
    • Fuel meter body seal.

    Also check for objects blocking MAF sensor inlet screen. Check for faulty or incorrectly installed PCV. If no problem was found, go to next step. If problem was found, repair or replace as necessary. After repair, go to step  22.

  8. Turn ignition on, with engine off. Using scan tool, observe Throttle Position (TP) sensor angle value. If zero percent is indicated, go to next step. If greater than zero percent is indicated, go to DTC P0121: TP SENSOR SYSTEM PERFORMANCE .
  9. Turn ignition off. Disconnect MAF sensor harness connector. Turn ignition on, with engine off. Using a DVOM, measure voltage between ground and MAF sensor signal circuit (Yellow wire) at MAF sensor harness connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step  11.
  10. Connect a test light between ground and MAF sensor ignition feed circuit (Pink wire) at MAF sensor harness connector. If voltage is about zero volts, go to step  14. If voltage is not about zero volts, go to step  13.
  11. If voltage reading from step  9 is less than 4.5 volts, go to step  15. If voltage reading is 4.5 volts or greater, go to next step.
  12. Turn ignition off. Disconnect VCM harness connectors. VCM is located on right side of engine compartment. Turn ignition on, with engine off. Using DVOM, measure voltage between ground and MAF sensor signal circuit (Yellow wire) at MAF sensor harness connector. If voltage is about zero volts, go to step  21. If voltage is not about zero volts, go to step  18.
  13. Connect test light between chassis ground and MAF sensor ignition feed circuit (Pink wire) at MAF sensor harness connector. If test light comes on, go to step  16. If test light does not come on, go to step  17.
  14. Check for poor connection(s) at MAF sensor. Repair as necessary. After repair, go to step  22. If connections are okay, go to step  19.
  15. Check MAF sensor signal circuit (Yellow wire) between VCM and MAF sensor for short to ground. Also check signal circuit for short to ground circuit (Black/White wire). Repair as necessary. After repair, go to step  22. If circuit is okay, go to step  21.
  16. Repair open in MAF sensor ground circuit (Black/White wire). After repair, go to step  22.
  17. Repair open in MAF sensor ignition feed circuit (Pink wire). After repair, go to step  22.
  18. Repair short to voltage in MAF sensor signal circuit (Yellow wire). After repair, go to step  22.
  19. Replace MAF sensor. After MAF sensor replacement, go to step  22.
  20. Replace MAP sensor. After MAP sensor replacement, go to step  22.
  21. Replace VCM. Program replacement VCM. See PROGRAMMING .
  22. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter DTC P0101. Operate vehicle within conditions required to set DTC. If scan tool displays RAN AND PASSED, go to next step. If scan tool does not display RAN AND PASSED, return to step  2.
  23. Using scan tool, read and record REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.
scientia non olet · About Mike's Workshop Manuals