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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 239 (ENGINE CONTROLS SELF-DIAGNOSTICS - 3.1L ENGINE)DIAGNOSTIC TESTSDTC P0103: MAF SENSOR CIRCUIT - HIGH FREQUENCYDIAGNOSTIC PROCEDURE
1999 GMC Forward Control 5.7 R, Automatic

Diagnostic Procedure

1999 GMC Forward Control 5.7 R, AutomaticSECTION 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. 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. 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 next step. If no, go to DIAGNOSTIC AIDS .
  3. Turn ignition switch to OFF position. Disconnect the MAF sensor harness connector. Start the engine. Observe the MAF sensor parameter using a scan tool. Is the MAF sensor parameter more than zero Hz? If yes, go to next step. If no, go to step  5.
  4. Turn ignition switch to OFF position. Check the MAF sensor harness for incorrect routing that is too close to the following components:
    • The secondary ignition wires or the coils.
    • Any solenoids.
    • Any relays.
    • Any motors.

    Did you find and correct the condition? If yes, go to step  10. If no, go to step  7.

  5. Turn ignition switch to OFF position. Check the air induction system for any water intrusion. Did you find and correct the condition? If yes, go to step  10. If no, go to next step.
  6. 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  10. If no, go to step  8.
  7. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  10. If no, go to step  9.
  8. Replace the MAF sensor. After repair, go to step  10.
  9. 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.
  10. 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.
  11. 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.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.