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Home >> Saturn >> 1999 >> SW2 Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - DTC P0100-P0134 >> DTC P0101 >> DTC P0101: MAF System Performance (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K", "L", "M", "P", "S" & "T" Series) >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
    2. NOTE: If any MAP or TP sensor related DTCs are set, diagnose affected DTCs first before proceeding with test. See appropriate DTC test.
  2. Turn ignition on, with engine off. Using scan tool, monitor MAP sensor value. If MAP sensor value is greater than 105 kPa, go to step  20. If MAP sensor value is not greater than 105 kPa, go to next step.
  3. Turn ignition off. Remove MAP sensor from intake manifold. Leave sensor harness connected. Start engine and slightly raise idle speed to prevent stalling during test. Using a hand-held vacuum pump, slowly apply vacuum up to 20 in. Hg. Each inch of applied vacuum should result in a 3-4 kPa decrease in MAP sensor value on scan tool. If MAP sensor value reading changes smoothly through entire range of test, go to next step. If MAP sensor value reading is erratic, go to step  20.
  4. With engine running, apply 20 in. Hg of vacuum to MAP sensor. If scan tool reading is 34 kPa or less, go to next step. If scan tool reading is not 34 kPa or less, go to step  20.
  5. With engine running, disconnect vacuum source from MAP sensor. If MAP sensor value matches BARO value on scan tool, go to next step. If values do not match, go to step  20.
  6. Check for the following conditions:
    • Objects blocking MAF sensor inlet screen.
    • Vacuum leaks in intake manifold, throttle body, EGR flange and pipes, MAP sensor seal, EVAP purge valve seal or fuel meter body seal.
    • Malfunctioning, missing or incorrectly installed PCV valve.

      Repair as necessary. After repairs, go to step  23. If no problems are found, go to next step.

  7. Turn ignition on, with engine off. Using scan tool, observe TP sensor angle. If TP sensor angle is zero percent, go to next step. If TP sensor angle is not zero percent, diagnose using DTC P0121.
  8. Turn ignition on, with engine off. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Monitor SPECIFIC DTC INFO for DTC P0101. If scan tool indicates that DTC P0101 FAILED THIS IGN, go to next step. If scan tool does not indicate that DTC P0101 FAILED THIS IGN, see DIAGNOSTIC AIDS .
  9. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on, with engine off. Using DVOM, measure voltage between signal circuit and ground circuit at MAF sensor harness connector. If voltage is about 5 volts, go to next step. If voltage is not as specified, go to step  11.
  10. Connect a test light between ignition positive feed circuit and ground circuit at MAF sensor harness connector. If test light illuminates, go to step  14. If test light does not illuminate, go to step  13.
  11. If voltage is less than 4.5 volts, go to step  15. If voltage is not as specified, go to next step.
  12. Turn ignition off. Disconnect VCM harness connector. Turn ignition on, with engine off. Using DVOM, measure voltage between ground and MAF sensor signal circuit at VCM harness connector. If voltage is about zero volts, go to step  22. If voltage is not as specified, go to step  18.
  13. Using a test light connected to chassis ground, probe ignition positive feed circuit at MAF sensor harness connector. If test light illuminates, go to step  16. If test light does not illuminate, go to step  17.
  14. Check for poor connection at MAF sensor. Repair as necessary. After repairs, go to step  23. If connection is okay, go to step  19.
  15. Check MAF signal circuit for an open, short to ground or short to MAF sensor ground circuit. Repair as necessary. After repairs, go to step  23. If circuit is okay, go to step  21.
  16. Repair open in MAF sensor ground circuit. After repairs, go to step  23.
  17. Repair open in MAF sensor ignition positive feed circuit. After repairs, go to step  23.
  18. Repair short to voltage in MAF sensor signal circuit. After repairs, go to step  23.
  19. Replace MAF sensor. After repairs, go to step  23.
  20. Replace MAP sensor. After repairs, go to step  23.
  21. Check for poor connections at VCM. Repair as necessary. After repairs, go to step  23. If connections are okay, go to next step.
  22. Replace VCM. Perform VCM, CKP and Passlock® reprogramming procedures. After repairs, go to next step.
  23. Using scan tool, clear DTCs. Start engine and allow it to reach normal operating temperature. Select SPECIFIC DTC, and then enter DTC P0101. Operate vehicle within the conditions for setting this DTC. See CIRCUIT DESCRIPTION . 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.
  24. 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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