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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 367 (Engine Controls Self-Diagnostics - 3.1L Engine) >> Diagnostic Tests >> DTC P0102: MAF Sensor Circuit - Low Frequency (Century & Grand PRIX) >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Start the engine. Observe the MAF Sensor parameter using the scan tool. Is the MAF Sensor parameter less than 1200 Hz? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running Test. CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
  4. Observe the Mass Airflow (MAF) sensor parameter using the 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 switch to OFF position. Check for the following conditions:
    • A restricted or collapsed air intake duct.
    • A misaligned air intake duct.
    • A dirty or deteriorating air filter element.
    • Any objects blocking the air inlet screen of the MAF sensor.
    • Any contamination or debris on the sensing elements of the MAF sensor.

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

  6. Check the fuse in the ignition 1 voltage circuit of the MAF sensor. See WIRING DIAGRAMS . Is the fuse open? If yes, go to step  14. If no, go to next step.
  7. Turn ignition switch to RUN position, engine OFF. Measure the battery voltage using a DMM. Disconnect the MAF sensor harness connector. Connect a test light between the MAF sensor ignition 1 voltage circuit and a good ground. Connect the DMM to the test light probe and a good ground. Is the voltage within 0.50 volt of battery voltage? If yes, go to next step. If no, go to step  21.
  8. Ensure all electrical components and accessories are turned OFF. Turn ignition switch to OFF position for 60 seconds to allow the control modules to power down. Measure the resistance from the MAF sensor ground circuit to a good ground using a DMM. Is the resistance less than 5 ohms? If yes, go to next step. If no, go to step  22.
  9. Turn ignition switch to RUN position, engine OFF. Measure the voltage between the MAF sensor signal circuit to a good ground using the DMM. Is the voltage 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 MAF sensor signal circuit and a good ground. Start the engine. Observe the DTC Information using a scan tool. Do any additional DTCs set? If yes, go to step  24. If no, go to next step.
  11. Turn ignition switch to OFF position. Connect the voltage supply and the ground lead of the Variable Signal Generator (J 38522), or equivalent, to the vehicle. Connect the Red lead of the variable signal generator to the MAF sensor signal circuit. Set the Duty Cycle switch of the variable signal generator to NORMAL. Set the Frequency switch of the variable signal generator to 5K. Set the Signal switch of the variable signal generator to 5 VOLTS. Start the engine. Observe the MAF Sensor parameter using a scan tool. Is the MAF Sensor parameter 4950-5025 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 switch to OFF position. Disconnect the Powertrain Control Module (PCM) harness connectors. 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  16.
  13. Is the voltage less than 4.8 volts? If yes, go to step 15. If no go to step  16.
  14. Test the ignition 1 voltage circuit for a short to ground. Did you find and correct the condition? If yes, go to step  28.
  15. Turn ignition switch to OFF position. Disconnect the PCM harness connectors. Test the signal circuit between the PCM and the MAF sensor for high resistance, an 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 switch to OFF position. Disconnect the PCM harness connectors. Turn ignition switch to RUN position, engine OFF. Measure the voltage from the signal circuit of the MAF sensor to a good ground using the DMM. 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 MAF sensor signal circuit to all other circuits at both PCM connectors using a DMM. Is the resistance less than infinity? 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 the wiring or the connector as needed. After repair, to step  28.
  21. Repair the high resistance or the open in the MAF sensor ignition 1 voltage circuit. After repair, to step  28.
  22. Repair the high resistance or the open in the MAF sensor ground circuit. After repair, to step  28.
  23. Repair the short to voltage in the MAF sensor signal circuit. After repair, to step  28.
  24. Repair the short between the MAF sensor signal circuit and the 5-volt reference circuit for which the DTC set. After repair, to step  28.
  25. Repair the circuits that are shorted together. After repair, to step  28.
  26. Replace the MAF sensor. After repair, to step  28.
  27. Replace PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  28. Clear the DTCs using a scan tool. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  29. Using the scan tool, observe the stored information in CAPTURE INFO. Are there any DTCs that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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