When checking service lights, which ones are essential to function properly?

The essential service lights that need to function properly when performing an exterior inspection of a vehicle include the brake lights, turn signal lights, and hazard lights. Each of these lights plays a critical role in ensuring the safety of the vehicle while on the road.

Brake lights are crucial as they signal to other drivers when a vehicle is slowing down or stopping, helping to prevent collisions. Turn signal lights indicate the driver’s intent to change lanes or make turns, allowing other road users to anticipate the vehicle's actions, thus promoting safer navigation in traffic. Hazard lights are important for alerting other drivers about potential dangers, especially in emergency situations when the vehicle is stationary or moving slowly.

While headlights and taillights, as well as other lights like fog lights and dashboard indicator lights, are important as well, the combination of brake lights, turn signals, and hazard lights ensures clear communication with other road users, directly contributing to overall traffic safety. Therefore, they are deemed essential in the context of a vehicle's operation and compliance with road safety regulations.