2015 Ram 2500 Auxilary fuel tank

I am hoping someone could shed some light on how an extra fuel tank would be wired. I just bought a 2015 Ram 2500 Laramie that had an extra 50 gallon fuel tank made by Transfer Flow the MaxFL model, in the bed. Well I tried to find a fuse for the pump to make calculation of fuel mileage easier but had no luck. Looked under the bed and it kind of looks like whoever wired it connected it though the existing wiring harness but I could be wrong. Looked at the web page and discovered that it pumps fuel in through the fill line where you would refuel from a pump when it senses the tank level to be approximately 3/8 full. I ended up unplugging three connectors at the top of the spare fuel tank, but would really like to know how it is wired<

Thanks,
Shelfish :confused013: