* Rear window defroster: Provides power to the grid in the rear window.
* Tail lights: Controls the power to the taillights, brake lights, and turn signals.
* Rear wiper/washer: Powers the rear wiper motor and washer pump.
* Trailer wiring (if equipped): Connects to the trailer harness for towing.
* Other rear accessories: Depending on options, this might include power for things like a rear cargo lamp, heated seats (if they are wired through this box), or other power outlets in the cargo area.
Essentially, it's a centralized location to manage the electrical circuits for rear vehicle functions, making troubleshooting and repairs more convenient than having these components wired directly to the main fuse box under the hood. If something stops working in the rear of your Explorer, the rear relay box is a good place to start investigating.
