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Home >> GMC >> 2003 >> Jimmy 2D Utility, Part Time, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 4.3L >> Diagnostic Tests >> DTC P0102: MAF Sensor Circuit - Low Frequency >> Diagnostic Procedures

Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Start engine. Observe the MAF sensor frequency with a scan tool. Is MAF sensor frequency less than 1200 Hz? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observed. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  4. Observe the MAF sensor frequency with a scan tool. Move the harness and the connector of the MAF sensor. Does the movement of the harness or the connector affect the MAF Sensor parameter? If yes, go to step  20. If no, go to next step.
  5. Turn ignition off. Inspect for the following conditions:
    • Restricted air intake duct.
    • Collapsed air intake duct.
    • Misaligned air intake duct.
    • Dirty air filter element.
    • A deteriorating air filter element.
    • Any objects blocking the air inlet screen of the MAF sensor.
    • Any debris on the sensing elements of the MAF sensor.
    • Any vacuum leak downstream of the MAF sensor.
    • A MAF sensor that is installed backwards.
    • A restricted exhaust system.

    Did you find and correct the condition? If yes, go to step  28. If no, go to next step.

  6. Inspect the fuse in the ignition 1 voltage circuit of the MAF sensor. Is the fuse open? If yes, go to step  14. If no, go to next step.
  7. Turn ignition on, with engine off. Measure the battery voltage with a DVOM. Disconnect the MAF sensor. Connect a test light between the ignition 1 voltage circuit of the MAF sensor and a good ground. Connect the DVOM to the probe of the test light and a good ground. Is the voltage less than battery voltage? If yes, go to step  21. If no, go to next step.
    8. NOTE: All electrical components and accessories must be turned OFF.
  8. Turn ignition off for 60 seconds to allow the control modules to power down. Measure the resistance from the ground circuit of the MAF sensor to a good ground with a DVOM. Is the resistance less than 5 ohms? If yes, go to next step. If no, go to step  22.
  9. Turn ignition on, with engine off. Measure the voltage from the signal circuit of the MAF sensor to a good ground with a DVOM. Is the voltage within 4.8-5.2 volts? If yes, go to next step. If no, go to step  13.
  10. Connect a 3-amp fused jumper wire between the signal circuit of the MAF sensor and a good ground. Start engine. Observe the DTC Information with a scan tool. Do any additional DTCs set? If yes, go to step  24. If no, go to next step.
  11. Turn ignition off. Connect the voltage supply and the ground lead of the Variable Signal Generator (J-38522) to the vehicle. Connect the Red lead of the signal generator to the signal circuit of the MAF sensor. Set the Duty Cycle switch to Normal. Set the Frequency switch to 5K. Set the Signal switch to 5 volts. Start engine. Observe the MAF Sensor parameter with a scan tool. Is the MAF Sensor parameter within 4950-5010 Hz? If yes, go to next step. If no, go to step  15.
    12. NOTE: An abnormal resistance on the signal circuit will disable the MAF sensor frequency before the voltage starts to drop out of the correct parameter of 4.8-5.2 volts.
  12. Turn ignition off. Disconnect the PCM. Test the MAF sensor signal circuit for a high resistance. Did you find and correct the condition? If yes, go to step  28. If no, go to step  18.
  13. Is the voltage less than 4.8 volts? If yes, go to step  15. If no, go to step  16.
    14. NOTE: The ignition 1 voltage circuit of the MAF sensor is spliced to other components of the vehicle.
  14. Repair ignition 1 voltage circuit for a short to ground. After repairs, go to step  28.
  15. Turn ignition off. Disconnect PCM. Test the signal circuit between the PCM and the MAF sensor for a high resistance, open circuit or short to ground. Did you find and correct the condition? If yes, go to step  28. If no, go to step  17.
    16. NOTE: Disconnecting the PCM connectors may eliminate the short to voltage if the signal circuit is shorted to another PCM circuit.
  16. Turn ignition off. Disconnect the PCM. Turn ignition on, with engine off. Measure the voltage from the signal circuit of the MAF sensor to a good ground with a DVOM. Is the voltage more than zero volts? If yes, go to step  23. If no, go to next step.
  17. Measure the resistance from the signal circuit of the MAF sensor to all other circuits at both PCM connectors with a DVOM. Is the resistance less than infinite? If yes, go to step  25. If no, go to step  19.
  18. Test for an intermittent and for a poor connection at the MAF sensor. Did you find and correct the condition? If yes, go to step  28. If no, go to step  26.
  19. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  28. If no, go to step  27.
  20. Repair wiring or connector as needed. After repairs, go to step  28.
  21. Repair high resistance or open in MAF sensor ignition 1 voltage circuit. After repairs, go to step  28.
  22. Repair high resistance or open in MAF sensor ground circuit. After repairs, go to step  28.
  23. Repair short to voltage in MAF sensor signal circuit. After repairs, go to step  28.
  24. Repair short between MAF sensor signal circuit and the 5-volt reference circuit for which the DTC set. After repairs, go to  28.
  25. Repair circuits that are shorted together. After repairs, go to step  28.
  26. Replace MAF sensor. See appropriate REMOVAL & INSTALLATION article. After repairs, go to step  28.
  27. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  28. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  29. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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