Why is my car overheating at idle or in heavy traffic?

Follow the wires from the fan (use the color codes on the wire). Find the relay and jump it out. If the fan runs, the relay is most likely bad. If it doesn’t it could be the fusable link or the fan is shot, or both (there’s typically a reason what the link goes bad.

The fan is wired hot, iirc. I believe that the relay provides the ground with a trigger from the PCM.