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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 92 (Engine Controls - Self-Diagnostics - 6.6L Diesel) >> Diagnostic Tests >> DTC P1404: EGR Valve Closed Pintle Position >> 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 Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC or within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
    3. NOTE: Mark all disconnected vacuum hoses for proper installation if necessary.
  3. Turn OFF the ignition. Disconnect the vacuum hose from the EGR vacuum vent solenoid outlet port to the EGR vacuum sensor. Install a hand held vacuum pump on the outlet port of the EGR vacuum vent solenoid. Apply 15 in. Hg vacuum. Does the vacuum hold steady? If yes, go to step  7. If no, go to next step.
    4. NOTE: Mark all disconnected vacuum hoses for proper installation if necessary.
  4. Disconnect the vacuum hose from the EGR vacuum vent solenoid inlet port. Install a vacuum gauge on the inlet port of the EGR vacuum vent solenoid. Apply 15 in. Hg vacuum. The solenoid should hold vacuum. Command the EGR Vent ON with a scan tool. The EGR vacuum vent solenoid should release the vacuum to 0 in. Hg. Does the EGR vacuum vent solenoid operate as described? If yes, go to next step. If no, go to step  9.
  5. Exit the Output Control Function on the scan tool. Compare the EGR Vacuum Sensor parameter to the BARO parameter with a scan tool. Is the EGR Vacuum Sensor parameter within 4 kPa of the BARO parameter? If yes, go to next step. If no, go to step  8.
  6. Inspect for the following conditions:
    • A stuck open EGR valve.
    • A restriction in the exhaust system causing a high back pressure condition.

    Did you find and correct the condition? If yes, go to step  10. If no, see DIAGNOSTIC AIDS .

  7. Replace the EGR vacuum vent solenoid. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to next step.
  8. Replace the EGR vacuum sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to next step.
  9. Replace the EGR valve vacuum control solenoid. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to next step.
  10. 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.
  11. 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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