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Home >> Chevrolet >> 1998 >> Astro Van Cargo, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0102 - MAF Sensor Circuit Low Frequency >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . Retrieve and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
  2. Start engine. With engine at idle, read MAF value using scan tool. If MAF value is less than 2 gm/s, go to step 4). If value is not less than 2 gm/s, go to next step.
  3. Turn engine off. Turn ignition on, engine off. Using scan tool, read and record FAIL RECORDS data. Operate vehicle within conditions noted in FAIL RECORD data. Using scan tool, read SPECIFIC DTC. If scan tool indicates that this DTC FAILED THIS IGN, go to next step. If scan tool does not indicate that this DTC FAILED THIS IGN, see DIAGNOSTIC AIDS.
  4. Check MAF fuse. If use is open, go to step 11). If fuse is okay, go to next step.
  5. Check for blockage in MAF sensor inlet screen. Check for vacuum leaks at intake manifold, throttle body or EGR valve flange and pipes. Check for crankcase valve faulty, missing or incorrectly installed. Repair as necessary. After repairs, go to step 16). If no faulty conditions exist, go to next step.
  6. Turn ignition off. Disconnect MAF sensor harness connector. Turn ignition on, engine off. Using a DVOM, check voltage between MAF sensor harness connector signal circuit and chassis ground. If voltage is about 5 volts, go next step. If voltage is not about 5 volts, go to step 10).
  7. Connect a test light between MAF sensor harness connector ignition feed and ground circuits. If test light illuminates, go to step 9). If test light does not illuminate, go to next step.
  8. Connect test light between MAF sensor harness connector ignition feed circuit and battery ground. If test light illuminates, go to step 12). If test light does not illuminate, go to step 13).
  9. Check for faulty connection at MAF sensor. Repair as necessary. After repairs are complete, go to step 16). If connection is okay, go to step 14).
  10. Check MAF sensor signal circuit between VCM and MAF sensor for open or short in circuit. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to step 15).
  11. Repair short to ground in MAF ignition voltage circuit. Replace fuse. After repairs, go to step 16).
  12. Repair open in MAF sensor ground circuit. After repairs, go to step 16).
  13. Locate and repair open MAF sensor ignition feed circuit. After repairs, go to step 16).
  14. Replace MAF sensor. After replacing sensor, go to step 16).
  15. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
  16. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter this DTC. Operate vehicle within conditions required to set DTC. If scan tool displays RAN AND PASSED, go to next step. If scan tool does not display RAN AND PASSED, repeat step 2).
  17. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.
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