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Home >> GMC >> 1997 >> Forward Control 4.3 W, L35, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 58 (Engine Controls - Tests W/Codes - 4.3L) >> Diagnostic Trouble Codes >> DTC P0102 - MAF Sensor Circuit Low Frequency >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 1997 GMC Savana, 1997 Chevrolet Chevy Van, and 1997 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform Powertrain On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Install scan tool. Start engine. With engine idling, monitor MAF display on scan tool. If MAF display is less than 2 gm/s, go to step 4). If MAF display is not less than 2 gm/s, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC for DTC P0102. If scan tool indicates DTC P0102 FAILED THIS IGN, go to next step. If scan tool does not indicate DTC P0102 FAILED THIS IGN, see DIAGNOSTIC AIDS.
  4. Check for the following conditions and repair as necessary:
    • Objects blocking MAF sensor inlet screen.
    • Intake manifold vacuum leaks.
    • Vacuum leaks at throttle body.
    • Vacuum leaks at EGR valve flange and pipes.
    • Crankcase ventilation valve faulty, missing or incorrectly installed.

    If a problem was found, go to step 14). If a problem was not found, go to next step.

  5. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on, with engine off. Using DVOM, check voltage between MAF signal circuit of MAF sensor connector and ground. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 9).
  6. Connect test light between MAF ignition feed and ground circuits at MAF sensor connector. If test light illuminates, go to step 8). If test light does not illuminate, go to next step.
  8. Connect test light between MAF ignition feed circuit at MAF sensor connector and battery ground. If test light illuminates, go to step 10). If test light does not illuminate, go to step 11).
  9. Check for poor connection at MAF sensor. Repair as necessary. After repairs, go to step 14). If connection is okay, go to step 12).
  10. Check for open, short to ground, short to MAF ground circuit or short to voltage in MAF signal circuit between MAF sensor and VCM. Repair as necessary. If MAF signal circuit is open or shorted, go to step 14). If MAF signal circuit is not open or shorted, go to step 13).
  11. Locate and repair open in the ground circuit to MAF sensor. After repairs, go to step 14).
  12. Locate and repair open in MAF ignition feed circuit to MAF sensor. After repairs, go to step 14).
  13. Replace MAF sensor. After replacing sensor, go to step 14).
  14. Replace VCM. Program replacement VCM using required equipment. After replacing and reprogramming VCM, go to next step.
  15. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0102. Operate vehicle within the conditions for setting this DTC. 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, repeat step 2).
  16. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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