Which system controls vehicle lighting?

• A. The braking system
• B. The electrical system
• C. The steering system
• D. The HVAC system

Answer: (B)

Lighting on a vehicle is powered and controlled by the electrical system. The battery provides the initial power, the alternator keeps it charged, and the wiring, fuses, relays, switches, and control modules route current to all lights—headlights, taillights, brake lights, turn signals, and interior illumination. When you turn on the headlights or activate a signal, the electrical circuits complete and current flows to the lamps, enabling them to operate. The other systems—braking, steering, and HVAC—have their own distinct controls and do not manage the lighting circuits, so they aren’t the system responsible for lighting.