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Home >> Buick >> 2007 >> Allure CX >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 3.8L - DTC P0350 To P2610 >> DTC P0406 >> Circuit/System Testing
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Circuit/System Testing

IMPORTANT: You must complete the Circuit/System Verification before proceeding with Circuit/System Testing.
  1. Ignition OFF, disconnect the EGR valve harness connector.
  2. Test for less than 3 ohms of resistance between the low reference circuit and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground, short to EGR control circuits, or an open/high resistance. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  4. Verify the EGR Position parameter is less than 1 percent.
    • If greater than the specified range, test the signal circuit for short to voltage. If the circuit tests normal, replace the ECM.
  5. Install a 3A fused jumper wire between the signal circuit and the 5-volt reference circuit. The EGR Position Sensor parameter should display more than 99 percent.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  6. If all circuits test normal, replace the EGR valve.
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