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Home >> Buick >> 2006 >> Lucerne CXS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 4.6L - DTC P0403 To DTC P1381 >> DTC P0412 >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition ON, the engine OFF and the solenoid enabled with a scan tool, observe the relay and the solenoid while manipulating all related wiring and connectors.
    • If manipulation does affect the relay or the solenoid then repair the harness or connector.
  2. Ignition ON, the engine OFF and the AIR CNTRL relay removed, connect a test lamp from the relay coil voltage supply circuit to ground, verify that the test lamp illuminates.
    • If the test lamp does not illuminate, test the voltage supply circuit for an open, high resistance or a short to ground.
  3. Ignition ON, the engine OFF and the AIR CNTRL relay removed, connect a test lamp from the relay coil voltage supply circuit to the relay control circuit, observe that the test lamp does not illuminate.
    • If the test lamp illuminates, test the control circuit for a short to ground. If the circuit test normal, replace the ECM.
  4. Ignition ON, the engine OFF, the AIR CNTRL relay removed, a test lamp connected from the relay coil voltage supply circuit to the relay control circuit and the AIR solenoid enabled with a scan tool, observe that the test lamp illuminates.
    • If the test lamp does not illuminate, test the relay control circuit for an open, high resistance or a short to voltage. If the circuit test normal, replace the control module.
  5. If all circuits and the control module test normal, replace the AIR CNTRL relay.
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