Mystery relay?

[AcesHigh]

Anybody know what this aftermarket relay(??) is? It’s mounted in front of my coolant reservoir on the passenger side and has wires routed over the engine against the firewall. The blue wire ties to the red going in the windshield wiper motor. One of the blacks attach to one of the starter relay hots. The other black runs to the back of the truck and is cut…. Almost certainly not original, but wanna make sure. It could have been for anything. Not sure why it’s on the passenger side.

 

[franklin2]

They wanted power to something at the back of the truck when the key was on. That relay is large, but the wire is smaller, so it could probably charge a battery to a trailer/camper or run a small inverter. The wire to the wiper motor is where they got a ignition key on hot power from. That activated the relay(if it was grounded) and the wire from the battery was the supply wire, going through the relay when it was active and going to the rear to do whatever they were doing with it.

If there are no fuses anywhere in this added wiring I would take it off immediately.