You may want to wait and see if someone with that vintage trailer shows up with advice.
AS RCREYES said, most of the newer units have a three position switch where the middle position is no power to anything and one position is power to lift and the other position is 12v power to the other stuff like lights, pump etc. Some years the "up" position was for the lift and some years it was down. You would have to experiment. The other rocker switch on the newer units operates the raising and lowering of the top. I don't know what you are speaking of when you say "key" to "on". I don't have a key nor have I heard of one.
Also, as RCREYES mentioned- the rising and lowering works off a battery. If you don't have a battery in it you should be able to jump to the cables in the battery compartment from your vehicle if that battery is good. But, "plugging it in" will do nothing for you if You don't have a battery and even then the battery needs to be charged. If you can post pictures of your switches etc it would be a help to others here who would then help you back.
Rick
What needs to be plugged in to raise my 1967 hi lo
Linear Mode
