igniton switch and the mystery of the dead battery

[Curtis-79MH]

My draining battery saga continues, but today I found out that the battery I was told was good was bad after all. So I bought a new gel battery which should be able to hold a charge. But I still have a drain on the gel battery (my engine starting battery)......
When I hooked up my new gel battery's neg. post I heard a click and traced it to the vacuum step solenoid. Thinking I may have found my mystery drain I tested the neg. post using a voltmeter (connected in-line between the battery and the neg. battery cable) and found it still pulls 12.7 volts from the neg. side. There is a drain REGARDLESS of whether the solenoid is connected or not.
So I have two questions:

Should the solenoid require juice even when the ignition is turned off? Hence, my click.
How can I easily disconnect the ignition switch to see if my drain is related to the ignition system/ vacuum switch?
I am on the hunt and will not give up until the battery drain is found....

[FrankR]

Chasing and finding electrical leaks is not real difficult with a plan. Da plan is .........
disconnect battery negative cable from battery. Connect a electric car horn to both the ground cable and the battery post. Connect with single piece of wire to each in any position. If there is ANY drain of that power source............the horn will beep until disconnected or load is removed. Some times the beep will increase with a heavy load.
When connecting a meter to check for any load the amps scale must be used. The battery reading found was battery voltage.........
I think most Airstream motor homes are wired as GM does the rest of their family of cars. The power for the ignition switch comes from the battery connection on the starter solenoid, inner fender mounted solenoid or a large connection block somewhere. GM uses mostly RED # 10 wires for the 12volt power leg. Red is always 12volt power in GM cars and trucks. Slowly removing fuses will sometimes tell what is working or not.....
On some GM cars, there has been problems where the RED #12 awg wire enters the body connector on the left front outside of the fire wall. Loose a couple screws and plug will be free to inspect.

[Curtis-79MH]

Thanks for your advice. So the reading I got with my volt meter when connected between the neg. battery post and the neg. battery cable was battery voltage? So I know I have a drain, but because the reading is battery voltage, I can't be sure how big a drain I have, correct? That is where your great horn idea comes in....the louder the honk the bigger the drain?? So I'll get the horn, and hope the honk isn't loud enough to attract the Canadian geese who are heading south. Thanks again for the great idea.

[winner]

We were having problems with the step on our Airstream 345 Motorhome running down our battery. At the factory, we were informed that is normal and if the step is left on the "ON" position it will run the engine battery down. Their suggestion was to always place the step in the OFF position when parked - no battery voltage drain will occur.