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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 87 (Engine Controls - Self-Diagnostics - 6.6L Diesel) >> Diagnostic Tests >> DTC P0201-P0208: Fuel Injector Control Circuits >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Observe the DTC information with a scan tool. Are DTCs P0201, P0204, P0206, P0207, or P0202, P0203, P0205, P0208 set? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observed. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Is DTC P1261 also set? If yes, go to step  13. If no, go to next step.
  5. Turn OFF the ignition. Disconnect the FICM. Probe the ignition voltage circuit for cylinders 2, 3, 5 and 8, with a test lamp connected to battery voltage. Does the test lamp illuminate? If yes, go to next step. If no, go to step  7.
  6. Disconnect each multi-way harness connector of the fuel injectors one at a time, while monitoring the test lamp. Does the test lamp turn OFF when any of the fuel injector harness connectors are disconnected? If yes, go to step  21. If no, go to step  33.
    7. NOTE: The DMM and test leads must be calibrated to 0 ohms in order to prevent misdiagnosis. Refer to the DMM User Manual for calibration procedure.
  7. Measure the resistance between the ignition voltage circuit and the injector command circuits for cylinders 2, 3, 5, and 8 with a DMM. Does the DMM display OL for all of the circuits? If yes, go to step  34. If no, go to next step.
  8. Does the DMM display OL for any of the circuits? If yes, go to step  23. If no, go to next step.
  9. Does the DMM display a resistance above 5 ohms for any fuel injector circuit? If yes, go to step  26. If no, go to next step.
  10. Does the DMM display a resistance below 0.3 ohms for any fuel injector circuit? If yes, go to step  27. If no, go to next step.
  11. Turn ON the ignition, with the engine OFF. Probe the ignition voltage circuit for cylinders 2, 3, 5 and 8, with a test lamp connected to ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  28.
  12. Disconnect each multi-way harness connector of the fuel injectors one at a time, while monitoring the test lamp. Does the test lamp turn OFF when any of the fuel injector harness connectors are disconnected? If yes, go to step  31. If no, go to step  30.
  13. Turn OFF the ignition. Disconnect the FICM. Probe the ignition voltage circuit for cylinders 1, 4, 6, and 7 with a test lamp connected to battery voltage. Does the test lamp illuminate? If yes, go to next step. If no, go to step  15.
  14. Disconnect each multi-way harness connector of the fuel injectors one at a time, while monitoring the test lamp. Does the test lamp turn OFF when any of the fuel injector harness connectors are disconnected? If yes, go to step  21. If no, go to step  33.
    15. NOTE: The DMM and test leads must be calibrated to 0 ohms in order to prevent misdiagnosis. Refer to the DMM User Manual for calibration procedure.
  15. Measure the resistance between the ignition voltage circuit and the injector command circuits for cylinders 1, 4, 6 and 7 with a DMM. Does the DMM display OL for all of the circuits? If yes, go to step  34. If no, go to next step.
  16. Does the DMM display OL for any of the circuits? If yes, go to step  23. If no, go to next step.
  17. Does the DMM display a resistance above 5 ohms for any fuel injector circuit? If yes, go to step  26. If no, go to next step.
  18. Does the DMM display a resistance below 0.3 ohms for any fuel injector circuit? If yes, go to step  27. If no, go to next step.
  19. Turn ON the ignition, with the engine OFF. Probe the ignition voltage circuit for cylinders 1, 4, 6 and 7, with a test lamp connected to ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  28.
  20. Disconnect each multi-way harness connector of the fuel injectors one at a time, while monitoring the test lamp. Does the test lamp turn OFF when any of the fuel injector harness connectors are disconnected? If yes, go to step  31. If no, go to step  30.
  21. Probe the fuel injector command circuit, for the cylinder that caused the test lamp to turn OFF, with a test lamp connected to battery voltage. Does the test lamp illuminate? If yes, go to step  32. If no, go to next step.
  22. Test both of the fuel injector circuits, of the isolated cylinder, between the fuel injector and the multi-way connector for a short to ground. Did you find and correct the condition? If yes, go to step  37. If no, go to step  29.
  23. Disconnect the multi-way connector of the fuel injector that displayed OL. Test the command circuit of the fuel injector, between the FICM and the multi-way connector, for the following:
    • An open circuit.
    • A poor connection.

    Did you find and correct the condition? If yes, go to step  37. If no, go to next step.

  24. Test the ignition voltage circuit of the fuel injector, between the multi-way connector and the splice, for the following:
    • An open circuit.
    • A poor connection.

    Did you find and correct the condition? If yes, go to step  37. If no, go to next step.

  25. Test both of the fuel injector circuits between the fuel injector and the multi-way connector for an open. Did you find and correct the condition? If yes, go to step  37. If no, go to step  29.
  26. Test for the following conditions:
    • Excessive resistance in the fuel injector circuits.
    • Poor connections at the multi-way connector of the fuel injector.

    Did you find and correct the condition? If yes, go to step  37. If no, go to step  29.

  27. Test for a short between the fuel injector ignition feed circuit, and the fuel injector command circuit. Did you find and correct the condition? If yes, go to step  37. If no, go to step  35.
  28. Inspect for poor connections at the harness connector of the FICM. Did you find and correct the condition? If yes, go to step  37. If no, go to step  36.
  29. Inspect for poor connections at the harness connector of the fuel injector. Did you find and correct the condition? If yes, go to step  37. If no, go to step  35.
  30. Repair the short to voltage in the ignition voltage circuit. After repairs, go to step  37.
  31. Repair the short to voltage in the fuel injector command circuit that turned OFF the test lamp. After repairs, go to step  37.
  32. Repair the short to ground in the fuel injector command circuit. After repairs, go to step  37.
  33. Repair the short to ground in the ignition voltage circuit. After repairs, go to step  37.
  34. Repair the open in the ignition voltage circuit. After repairs, go to step  37.
  35. Replace the appropriate fuel injector. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  37.
  36. Replace the FICM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to next step.
  37. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  38. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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