[Fulltiming]

On mine, the block heater is plugged into an electric outlet in the engine compartment. I would first try unplugging the block heater, assuming you have one, then resetting the breaker. The lights in the lower compartments are typically 12 volt DC rather than 120 VAC. However, if none of the electric outlets in the bays on the passenger side work, I would also unplug everything plugged into them. If the breaker will then reset, you can start plugging things back in until the breaker trips and you have your culprit. If the breaker trips with everything unplugged from the outlets that are all new empty, you most likely have a short in the wiring circuit itself or in one of the outlets. Occasionally, a breaker will get to the point, particularly if there have been a number of trips in the past where they will not lock well. In those cases, replacing the breaker itself is necessary.