[Kevin_NJ]

The controller needs a 12V source that should only be live when the ignition is on. You need to track down where that is. Installers use various sources for it. Sometime a fuse inside the cab, sometimes a fuse under the hood, sometimes they tap into a wire. Too often they do a poor job of it and it come loose. There should be an inline fuse for that as well.

Start at the controller and follow the wiring loom towards the engine bay. At one point that 12V supply will leave the rest of the wire loom.

A good test light and/or meter is good too.

You can find wiring diagrams on BOSS' website. They will show you which pin at the controller connection needs that ignition source power.