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Home >> Buick >> 2007 >> Allure CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 61 (Engine Control System & Fuel System - 3.8L - Troubleshooting & Diagnosis) >> Malfunction Indicator Lamp (MIL) Diagnosis >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the instrument cluster.
  2. Ignition ON, verify that a test lamp illuminates between the ignition circuit and ground.
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all components connected to the fuse and replace as necessary.
  3. Connect a test lamp between the control circuit and the ignition circuit.
  4. Command the MIL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the PCM.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PCM.
  5. If all circuits test normal, replace the instrument cluster.
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