What should you do first when approaching a traffic signal that is not functioning?

When encountering a traffic signal that is not functioning, the appropriate action is to treat it as a stop sign. This means coming to a complete stop at the intersection, allowing time to look for other vehicles, cyclists, or pedestrians before proceeding. This approach ensures that all road users can safely navigate the intersection, as treating the non-functioning signal as a stop sign helps to maintain order and prevents accidents.

Treating it as a stop sign also aligns with traffic laws in many jurisdictions, which mandate that drivers must stop at non-functioning signals. It emphasizes the importance of caution and awareness in situations where traffic control devices are out of service.

The other options suggest either inadequate caution or improper handling of the situation, which can lead to confusion and increase the risk of collisions at intersections.