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Circuit/System Testing

WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON, verify that the Stoplamp Pedal Switch parameter in the ECM reads Applied while depressing the brake pedal.
    • If the parameter reads Released, test the stop lamp switch signal circuit for a short to ground, an open/high resistance. If the circuit tests normal, replace the ECM.
  2. Ignition ON, release the brake pedal, verify that the Stoplamp Pedal Switch parameter reads Released.
    • If the parameter reads Applied, test the stop lamp switch signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  3. If all circuits test normal, replace the ECM.
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