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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 234 (ENGINE CONTROLS - SELF-DIAGNOSTICS)DIAGNOSTIC TESTSDTC P0403: EGR VALVE CONTROL CIRCUITDIAGNOSTIC PROCEDURES
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8

Diagnostic Procedures

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 Cadillac Seville and 2003 Cadillac DeVille. 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. Turn ignition on, with engine off. Command the EGR from zero percent to 100 percent with a scan tool. Does the EGR POSITION SENSOR parameter remain with in 3 percent of the DESIRED EGR POSITION parameter when commanded with a scan tool? If yes, go to next step. If no, go to step  4.
  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. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Turn ignition off. Disconnect the EGR. Turn ignition on, with engine off. Probe the EGR valve high control circuit with a test light connected to a good ground. Command the EGR 0-10 percent with a scan tool. Does the test light turn on at 10 percent and off at zero percent when commanded with a scan tool? If yes, go to next step. If no, go to step  6.
  5. Connect a test light between the EGR valve high control circuit and the EGR valve low control circuit. Command the EGR 0-10 percent with a scan tool. Does the test light illuminate? If yes, go to step  10. If no, go to step  9.
  6. Does the test light remain illuminated when the EGR valve is commanded to zero percent with a scan tool? If yes, go to step  8. If no, go to next step.
  7. Test the EGR valve high control circuit for a short to ground or an open. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  8. Test the EGR valve high control circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  9. Test the EGR valve low control circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  10. Test for an intermittent and/or poor connections at the EGR valve. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  11. Test for an intermittent and/or poor connections at the PCM. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Replace the EGR valve. See EGR VALVE under EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL & INSTALLATION - DEVILLE & SEVILLE article. Did you complete the replacement? If yes, go to step  14.
  13. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - DEVILLE & SEVILLE article. Did you complete the replacement? If yes, go to next step.
  14. Clear the DTCs with a scan tool. Turn off the ignition for 30 seconds. Start the engine and operate vehicle within the Conditions For Running DTC. You may also operate vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle? If yes, go to step  2. If no, go to next step.
  15. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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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.