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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 77 (Engine Controls Self-Diagnostics - 5.0L & 5,7L) >> Diagnostic Tests >> DTC P1404: EGR Valve Closed Pintle Position >> Diagnostic Procedures

Diagnostic Procedures

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  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. Turn ON the ignition, with the engine OFF. Install the scan tool. Command the EGR valve to 20%, 50%, 70%, 100% and back to 0 percent. Does the Actual EGR Position follow the Commanded EGR Position and return to 0 percent? If yes, go to next step. If no, go to step  4.
  3. This DTC is intermittent. Are any additional DTCs stored? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, see DIAGNOSTIC AIDS .
  4. Disconnect the EGR valve harness connector. Is the Actual EGR Position near 0%? If yes, go to step  6. If no, go to next step.
  5. Check the EGR valve pintle position signal circuit for a short to voltage. Repair as necessary. Did you find a problem? If yes, go to step  12. If no, go to step  11.
  6. Probe the EGR valve 5-volt reference circuit at the EGR valve harness connector with a DMM connected to a ground. Is the voltage near 5.2 V? If yes, go to next step. If no, go to step  8.
  7. Probe the EGR valve control circuit at the EGR valve harness connector with a test lamp connected to a ground. Is the test lamp ON? If yes, go to step  9. If no, go to step  10.
  8. Check the EGR valve 5-volt reference circuit for a short to voltage. Repair as necessary. Did you find a problem? If yes, go to step  12. If no, go to step  11.
  9. Check the EGR valve control circuit for a short to voltage. Repair as necessary. Did you find a problem? If yes, go to step  12. If no, go to step  11.
  10. Replace the EGR valve. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  12.
  11. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  12. Clear the DTCs with a scan tool. Turn OFF the ignition. 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.
  13. 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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