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Home >> Buick >> 2002 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.1L Engine >> Diagnostic Tests >> DTC P0201-P0206: Injector Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Clear the DTCs with a scan tool. Idle the engine at the normal operating temperature. Monitor the misfire current counters with a scan tool. Are any of the misfire current counters incrementing? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC or as close as possible to the Freeze Frame/Failure Records that you observed. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
  4. Turn ignition off. Disconnect the fuel injector harness multi-way connector. Jumper the three Camshaft Position (CMP) sensor circuits between the fuel injector harness multi-way connectors. Probe the appropriate fuel injector control circuit, at the PCM side, of the fuel injector harness multi-way connector with a test light connected to B+. Crank the engine. Does the test light blink when cranking the engine? If yes, go to step  8. If no, go to next step.
  5. Does the test light remain illuminated at all times? If yes, go to step  7. If no, go to next step.
  6. Test the control circuit of the fuel injector for a short to voltage or an open between the multi-way connector and the PCM. Did you find and correct the condition? If yes, go to step  18. If no, go to step  14.
  7. Test the control circuit of the fuel injector for a short to ground between the multi-way connector and the PCM. Did you find and correct the condition? If yes, go to step  18. If no, go to step  17.
  8. Inspect the accessible fuel injector jumper harness between the multi-way connector and the plenum for the following conditions: Poor connections at the multi-way connector, damaged or pinched wiring, or broken wires inside the insulation. Did you find and correct the condition? If yes, go to step  18. If no, go to next step.
  9. Remove upper intake manifold. See appropriate article in ENGINES. Probe the appropriate fuel injector control circuit, fuel injector side, at the multi-way connector, with a test light connected to B+. Does the test light illuminate? If yes, go to step  15. If no, go to next step.
  10. With a DMM, test for continuity between the ignition voltage terminal and the appropriate fuel injector control circuit terminal, at the multi-way connector. Does the DMM indicate OL? If yes, go to next step. If no, go to step  13.
  11. Test the control circuit of the fuel injector for an open, or poor connections at the fuel injector. Did you find and correct the condition? If yes, go to step  18. If no, go to next step.
  12. Test the ignition voltage circuit of the fuel injector for an open between the fuel injector and the splice. Did you find and correct the condition? If yes, go to step  18. If no, go to step  16.
  13. Test the control circuit of the fuel injector for a short to voltage, or a short to another circuit. Did you find and correct the condition? If yes, go to step  18. If no, go to step  16.
  14. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step  18. If no, go to step  17.
  15. Repair the short to ground in the fuel injector control circuit. After repairs, go to step  18.
  16. Replace the appropriate fuel injector. After repairs, go to step  18.
  17. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  18. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . If yes, go to next step. If no, go to step  2.
  19. Using scan tool, observe the stored information and Capture Info. If scan tool displays any undiagnosed DTCs, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
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