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Home >> Chevrolet >> 2006 >> Chevy Express G2500, Van Cargo Extended, 6.6 2 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 6.6L (LLY) - DTC P0401 To DTC P268A >> DTC P046C >> Circuit/System Testing

Circuit/System Testing

  1. Test the following EGR circuits for resistance over 10 ohms.
    • The 5-volt reference circuit
    • The low reference circuit
    • The motor low control circuit
    • The motor high control circuit
    • If any circuit is more than 10 ohms repair as necessary.
  2. Disconnect the EGR valve connector, connect jumper wires between the EGR valve and the EGR valve harness connector for the 5-volt reference circuit, signal circuit, and the low reference circuit. Connect a test lamp between the EGR motor low control circuit and the EGR motor high control circuit on the EGR harness connector. Turn the ignition ON, the test lamp should flash ON and OFF.
    • If the test lamp does not flash replace the ECM.
  3. Remove the EGR valve and inspect for debris that will cause the EGR to stick and clean as necessary.
    • If the EGR valve is sticking, has a weak spring, or is damaged and cannot be cleaned replace the EGR valve.
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