Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2003 Cadillac CTS AutomaticFACTORY OEM SERVICE PROCEDURE
Lighting DTCS
LIGHTING DIAGNOSTIC TROUBLE CODE (DTC) LIST
| DTC | Description |
|---|---|
| DTC B2556 | Interior Lamp Rheostat Voltage |
| DTC B2575 | Arc Tube Voltage Supply Circuit |
| DTC B2646 | Twilight Sensor Voltage |
| DTC B3410 | Headlamp Leveling Control Module |
| DTC B3420 | Headlamp Leveling Control Module |
| DTC P0504 | TCC Brake Switch/Cruise Control Input Mismatch |
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.