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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 87 (Lighting System - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> Stop Lamps Malfunction >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON/vehicle in service mode, verify the scan tool Brake Pedal Applied parameter changes between Active and Inactive while pressing and releasing the brake pedal.
    • If the parameter does not change 

      Refer to Circuit/System Testing - Brake Pedal Position Sensor Malfunction.

    • Go to next step: If the parameter changes 
  2. Verify the left and right brake lamps turn ON and OFF when commanding the left and right turn signal/stop lamps ON and OFF with a scan tool.
    • If the brake lamps do not turn ON and OFF 

      Refer to Circuit/System Testing - Stop Lamps Malfunction.

    • Go to next step: If the brake lamps turn ON and OFF 
  3. Verify the center high mounted stop lamp turns ON and OFF when commanding the Center Stop Lamp ON and OFF with a scan tool.
    • If the center high mounted stop does not turn ON and OFF 

      Refer to Circuit/System Testing - Center High Mounted Stop Lamp Malfunction.

    • Go to next step: If the center high mounted stop turns ON and OFF 
  4. A fault is not currently present and may be an intermittent condition
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