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Home >> Chevrolet >> 2006 >> Impala SS >> Repair and Diagnosis >> External Pages >> Different car >> Section 439 (Lighting System) >> Diagnostic Information and Procedures >> DTC B3903 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 Saturn Sky. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the CHMSL.
  2. Connect a test lamp between the stop lamp switch signal circuit terminal A and ground.
  3. Ignition ON, apply the brake pedal ON and OFF. The test lamp should turn ON and OFF as the brake pedal is applied and released.
    • If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
    • If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, replace the CHMSL.
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