Circuit/System Testing

2013 Buick Regal Turbo Premium, Standard TransSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2011 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X1 (LAF/LF1) or X2 (LLT) harness connector at the K20 ECM.
  2. Connect a test lamp between the appropriate signal circuit terminal listed below and ground.
    • Terminal 57 (LAF/LF1)
    • Terminal 52 (LLT)
  3. Ignition ON, verify the test lamp turns ON and OFF when pressing and releasing the brake pedal.
    • If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
    • 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 K9 BCM.
  4. If all circuits test normal, replace the K20 ECM.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.