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Home >> Buick >> 2011 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 249 (Lighting System) >> Diagnostic Information and Procedures >> DTC B3884 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2011 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the center high mounted brake lamp.
  2. Test for less than 5 Ω between the ground circuit terminal B and ground.
    • If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal A and ground.
  4. Command the Center Brake Lamp Command test 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 voltage. If the circuit tests normal, replace the BCM.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, replace the center high mounted brake lamp.
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