Final answer:
When a motorist comes across an unlit signal, they should stop and proceed cautiously, treating the situation as a four-way stop to ensure safety and prevent accidents.
Step-by-step explanation:
A motorist approaching an unlit signal should proceed with extreme caution. In the absence of traffic signals or if they are not functioning, intersections become comparable to a four-way stop in many regions, meaning that the driver should stop completely and only proceed when it is safe to do so. This is particularly important for ensuring pedestrian safety and managing the speeds at which vehicles travel to prevent accidents, which could rise significantly without a working signal as indicated by traffic accident reports.