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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Isuzu Trooper. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform ON-BOARD DIAGNOSTIC II SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
  2. Turn ignition off. Disconnect Mass Airflow (MAF) sensor 3-pin harness connector E-6. MAF sensor is located in air intake pipe, at air cleaner housing. Connect test light between MAF sensor harness connector terminal No. 2 (Black/Blue wire) and No. 3 (Black/Yellow wire). See Fig 1. Turn ignition on. If test light does not illuminate, leave ignition on and go to next step. If test light illuminates, go to step  6.
  3. Using DVOM, measure voltage between MAF sensor harness connector terminal No. 2 (Black/Blue wire) and No. 3 (Black/Yellow wire). See WIRING DIAGRAMS article. Voltage should be 11.5-12.5 volts. If voltage is not as specified, go to next step. If voltage is as specified, go to step  5.
  4. Turn ignition off. Check for open or short to ground in Black/Yellow wire between MAF sensor and engine fuse No. C-8 (15-amp). See WIRING DIAGRAMS article. If problem is found, repair circuit as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM.
  5. Check for open or short to ground in Black/Blue wire between ground point G117 and MAF sensor. See WIRING DIAGRAMS article. Ground point G117 is located on top right rear of engine. If problem is found, repair circuit as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM.
  6. Turn ignition off. Check for open or short to ground or short to voltage in Yellow wire between PCM and MAF sensor. See WIRING DIAGRAMS article. If no problem is found, go to next step. If problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM.
  7. Connect MAF sensor harness connector. Connect TECH 2 or equivalent scan tool to DLC. DLC is located under left side of instrument panel. Place transmission in Park or Neutral and apply parking brake. Start and idle engine. Using scan tool, observe MAF sensor parameter. If parameter displays 3-7 grams/sec., go to next step. If parameter does not display 3-7 grams/sec., go to step  9.
  8. Turn ignition off. Disconnect MAF sensor 3-pin harness connector. Start and idle engine. On scan tool, observe MAF sensor parameter. If parameter displays any value other than zero grams/sec., go to next step. If parameter displays zero grams/sec., go to step  10.
  9. Replace MAF sensor. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM.
  10. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE REPLACEMENT  under POWERTRAIN CONTROL MODULE. Use scan tool to clear DTC and verify repair.
Fig 1: Identifying Mass Airflow Sensor Harness Connector Terminals
G00077223Courtesy of ISUZU MOTOR CO.
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