Fred,
Thanks for the guidance, after three days of "Winter" down here in south Texas, I crawled under our coach this afternoon to take a closer look at the offending step. As you mentioned, a 4 wire square plug, with Red, White, Yellow and Brown wires. There is also a relay prior to the square plug with the Yellow, I assume Ignition, coming in and going out, and a ground. Instead of cutting the yellow wire I disconnected it from the relay hoping for success, but alas, the step continued to extend and retract with the ignition switch off, the Yellow Ignition wire removed from the circuit, and the Entry Step switch off.
There is a lot of rust and corrosion around the step as it is aft of the right front tire, but all that road grime is to be expected. No idea who, but someone is telling the step that the engine is running, should a new controller be on my shopping list?
Thanks again for all your help