Three way switch
 

I keep seeing references to a three way switch. Where is it located and what does it do. I have a 3389B trailer.

Near the entrance door ,down low, next to the raise and lower switch and release cable.

Your HiLo may not have it, they changed the switch arrangement somewhere along the way. Someone may come along and fill you in on that.

the only thing by the up and down switch is the down release cable and a red light.

To actually answer your question, now that I have read it again, the three way rocker switch controls power to either the lift circuit or the 12 volt systems to the rest of the trailer. Up position to 12 volts, middle position all off, and bottom position to lift system.