When should the stoplights on a vehicle activate?

The stoplights on a vehicle are designed to activate when the brake pedal is pressed. This is an essential safety feature that alerts other drivers behind the vehicle that it is slowing down or coming to a stop. The illuminated stoplights provide a clear signal, helping to prevent rear-end collisions by ensuring that following vehicles have adequate warning to react accordingly.

When discussing the other choices, the option about the vehicle being in reverse is related to a different set of lights known as reverse lights, which indicate that the vehicle is moving backward rather than signaling a stop. The choice regarding the engine being running is also not relevant because the stoplights function independently of the engine operation; as long as the brake pedal is engaged, the stoplights will activate regardless of the engine's status. Lastly, stating that the stoplights should be on at all times while driving does not reflect standard practice since they should only activate when braking to avoid confusion for other drivers.