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HOMESERVICE MANUALSPONTIAC1997GRAND PRIX GTP, 4D SEDANREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 1 (ENGINE CONTROLS - TESTS W/CODES - 3.1L ENGINE)DIAGNOSTIC TROUBLE CODESDTC P1200 - INJECTOR CONTROL CIRCUITDIAGNOSTIC PROCEDURES
1997 Pontiac Grand Prix GTP, 4D Sedan

Diagnostic Procedures

1997 Pontiac Grand Prix GTP, 4D SedanSECTION Diagnostic Procedures
WARNING: This page is about a different variant/trim than selected.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING - 3.1L article. Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. Go to next step.
  2. Start engine and allow it to idle. Using scan tool, select SPECIFIC DTC INFO for DTC P1200. If scan tool displays DTC P1200 FAILED THIS IGN, go to step 4). If scan tool does not display DTC P1200 FAILED THIS IGN, go to next step.
  3. Turn engine off. Turn ignition on, engine off. Read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1200. If scan tool displays DTC P1200 FAILED THIS IGN, go to next step. If scan tool does not display DTC P1200 FAILED THIS IGN, see DIAGNOSTIC AIDS.
  4. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a DVOM, check voltage between each injector driver circuit and engine ground. If voltage is 9-16 volts on each circuit, go to next step. If voltage is not as specified on any circuit, go to step 9).
  5. Perform INJECTOR BALANCE TEST under FUEL SYSTEM in the SYSTEM/COMPONENT TESTS article. If injectors are okay, go to next step. If an injector problem is found, go to step 17).
  6. Turn ignition off. Disconnect all injector connectors. Turn ignition on. Using DVOM, check voltage between each injector driver circuit at PCM harness connector and engine ground. If voltage is zero volts on each circuit, go to next step. If voltage is not as specified, go to step 16).
  7. Check harness ignition feed circuits between injector fuse and injectors for intermittent open. Check injector driver circuits between PCM and injectors for intermittent open or short to ground. If a problem is found, repair as necessary. After repairs, go to step 19). If no problem is found, go to next step.
  8. Check for faulty connection at injector connectors. Check injector driver circuits for faulty connection at PCM connectors. If a problem is found, go to step 19). If no problem is found, go to step 18).
  9. Turn ignition off. Disconnect affected injector connector(s). Turn ignition on. Check voltage between ignition feed circuit at affected injector connector(s) and engine ground. If voltage is 9-16 volts, go to next step. If voltage is not as specified, go to step 14).
  10. Connect a test light between affected injector connector(s) and battery voltage. If test light illuminates, go to step 15). If test light does not illuminate, go to next step.
  11. Turn ignition off. Connect a fused jumper cable between affected injector connector(s) ignition feed and driver circuits. Turn ignition on. Connect test light between affected injector(s) driver circuit at PCM and engine ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
  12. Check for faulty connection at injector connector(s). If faulty connection is found, repair as necessary. After repairs, go to step 19). If connection(s) are okay, go to step 17).
  13. Locate and repair open in affected injector driver circuit(s). After repairs, go to step 19).
  14. Locate and repair open or short to ground in affected ignition feed circuit(s). After repairs, go to step 19).
  15. Locate and repair short to ground in affected injector driver circuit(s). After repairs, go to step 19).
  16. Locate and repair short to voltage in affected injector driver circuit(s). After repairs, go to step 19).
  17. Replace faulty injector(s). After replacing injector(s), go to step 19).
  18. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  19. Using scan tool, read and record FAIL RECORDS DATA, and clear DTCs. Operate vehicle within conditions noted in FAIL RECORDS data. Using scan tool, select SPECIFIC DTC INFO for DTC P1200. If scan tool displays DTC P1200 FAILED THIS IGN, return to step 2). If scan tool does not display DTC P1200 FAILED THIS IGN, repair is complete.
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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.