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Home >> Buick >> 1996 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - 3.1L >> Diagnostic Trouble Codes >> DTC P1200 - Injector Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Start engine and allow it to idle. Using scan tool, monitor SPECIFIC DTC info for DTC P1200 until DTC P1200 test runs. If scan tool indicates FAILED THIS IGN, go to step 4). If scan tool does not indicate FAILED THIS IGN, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for DTC P1200 until DTC P1200 test runs. If scan tool indicates FAILED THIS IGN, go to next step. If scan tool does not indicate FAILED THIS IGN, see DIAGNOSTIC AIDS.
  4. Install Injector Test Harness (J-34730-380) and Adapter Harness (J 34730-385) to injector 10-way connector. Attempt to start engine. If ALL injector test LEDs flash, go to next step. If not, go to step 6).
  5. Using Fuel Injector Coil Tester (J-39021), check injector coil voltage and repair as necessary. After repairs, go to step 12).
  6. If some of the injector LEDs flashed, go to step 8). If none flashed, go to next step.
  7. Check injector feed circuit between fuse and 10-way connector for open or short to ground. Repair as necessary and go to step 12). If no repairs are required, go to step 9).
  8. Check injector drive circuits for injectors which did not flash LED for open, short to ground, or short to voltage. Repair as necessary and go to step 12). If no repairs are required, go to step 10).
  9. Check for poor terminal connections. Repair as necessary and go to step 12).
  10. Check for poor terminal connections at injectors. Repair as necessary and go to step 12). If no repairs are required, go to next step.
  11. Replace PCM. Reprogram PCM using required equipment. After repairs, go to step 12).
  12. Review and record scan tool FAIL RECORDS data. Clear DTCs. Operate vehicle under conditions which set DTC. Monitor scan tool SPECIFIC DTC info for DTC P1200. If scan tool indicates DTC failed this ignition, go to step 2). If not, repair is complete. If driveability symptom exists, go to TESTS W/O CODES article.
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