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Home >> GMC >> 2001 >> Jimmy 2D Utility, 4WD, Standard >> 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 powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
  2. Start engine. Using scan tool, observe MAF sensor frequency. If MAF sensor frequency is less than 1300 Hz, go to step  4. If MAF sensor frequency is not less than 1300 Hz, go to next step.
  3. Observe FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start and operate vehicle within the conditions for running the DTC or as close to FREEZE FRAME/FAILURE RECORDS data. See CODE ENABLE CRITERIA . If DTC resets, go to next step. If DTC does not reset, see DIAGNOSTIC AIDS .
  4. Observe MAF sensor frequency on scan tool. Move MAF sensor harness and connector. If movement of harness or connector affects MAF sensor frequency, go to step  25. If movement of harness or connector does not affect MAF frequency, go to next step.
  5. Turn ignition off. Check for restricted air intake duct, collapsed air intake duct, misaligned air intake duct, dirty air filter element, deteriorating air filter element, any objects blocking air inlet screen of MAF sensor, debris on sensing elements of MAF sensor, vacuum leak downstream of MAF sensor, MAF sensor installed backwards, or restricted exhaust system. Repair as necessary. After repairs, go to step  30. If no problem is found, go to next step.
  6. Check ENG 1 fuse in the ignition 1 voltage circuit of MAF sensor. Fuse is located in underhood fuse block. If fuse is open, go to step  12. If fuse is okay, go to next step.
  7. Disconnect MAF sensor harness connector. MAF sensor is located in air intake. Turn ignition on, with engine off. Connect a test light between a good ground and MAF sensor harness connector terminal "C" (Pink wire). See Figure. Does the test light illuminates, go to next step. If test light does not illuminate, go to step  17.
  8. Connect test light between MAF sensor harness connector terminals "B" (Black wire on "L" and"M" Series or Black/White wire on "S" and "T" Series). If test light illuminates, go to next step. If test light does not illuminate, go to step  18.
  9. Check voltage between a known-good ground and MAF sensor harness connector terminal "A" (Yellow wire). If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step  11.
  10. Connect a fused jumper wire between a known-good ground and MAF sensor harness connector terminal "A" (Yellow wire). Start engine. Using scan tool, check if any additional DTCs are set. If additional DTCs are set, go to step  23. If no additional DTCs are set, go to step  26.
  11. If voltage is less than 4.5 volts, go to step  13. If voltage is not less than 4.5 volts, go to step  15.
    12. NOTE: The ignition 1 voltage circuit (Pink wire) of the MAF sensor is spliced to other components of the vehicle.
  12. Using a DVOM, check for continuity of Pink wire between MAF sensor and ground. If continuity exists, go to step  16. If continuity does not exist, go to step  26.
  13. Turn ignition off. Disconnect PCM harness connector C2. Check for high resistance or open in Yellow wire between MAF sensor harness connector terminal "A" and PCM harness connector C2, terminal No. 31. See Figure and Figure . If continuity exists, go to next step. If continuity does not exist, go to step  19.
  14. Check Yellow wire for continuity to ground. If continuity exists, go to step  21. If continuity does not exist, go to step  16.
    15. NOTE: Disconnecting PCM harness connectors may eliminate the short to voltage if signal circuit is shorted to another PCM circuit.
  15. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, with engine off. Check voltage between a known-good ground and MAF sensor harness connector terminal "A" (Yellow wire). If voltage reading is about zero volts, go to next step. If voltage reading is not about zero volts, go to step  22.
  16. Check for continuity between PCM harness connector C2 terminal No. 31 and MAF sensor harness connector terminal "A" (Yellow wire). If continuity exists, go to step  24. If continuity does not exist, go to  27.
  17. Turn ignition off. Repair short to ground in Pink wire. Replace fuse as necessary. After repairs, go to step  30.
  18. Turn ignition off. Repair open in Pink wire. After repairs, go to step  30.
  19. Repair high resistance or open in Black wire ("L" and "M" Series) or Black/White wire ("S" and "T" Series). After repairs, go to step  30.
  20. Repair high resistance or open in Yellow wire. After repairs, go to step  30.
  21. Repair short to ground in Yellow wire. After repairs, go to step  30.
  22. Replace MAF sensor. After replacing sensor, go to step  30.
  23. Turn ignition off. Repair short to voltage in Yellow wire. After repairs, go to step  30.
  24. Repair circuits that are shorted together. After repairs, go to step  30.
  25. Turn ignition off. Repair harness or connections as needed. After repairs, go to step  30.
  26. Check for intermittent and poor connection at MAF sensor. Repair as necessary. After repairs, go to step  30. If no problem is found, go to step  28.
  27. Check for intermittent and poor connection at PCM. Repair as necessary. After repairs, go to step  30. If no problem is found, go to step  29.
  28. Replace MAF sensor. After replacing sensor, go to step  30.
  29. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  30. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start and operate vehicle within the conditions for running the DTC. See CODE ENABLE CRITERIA . If DTC runs and passes, go to next step. If DTC resets, go to step  2.
  31. Using scan tool, observe the stored information and Capture Info. If scan tool displays any undiagnosed DTCs, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
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