A resistance test between terminals unfortunately doesn't help much. There are a lot of parallel loads on the battery which would make a ohms reading difficult to pin down. An amp test will help some to give you an idea of how fast the battery will drain down. Either way finding the load isn't always a simple process. More or less you're going to need to start disconnect stuff or pulling fuses and do a current test over until you find the problem.
Concerning the steps. They work pretty much the same as power windows in a car. No micro switches to sense position and such. The step controller works by sensing how much current the motor is demanding. Once the current reaches a preset level the controller will shut off power but there's a catch. When the voltage to the system drops the current required to do the same amount of work will increase. The catch is the controller only senses current. So a low battery will screw things up with lower voltage. Also a poor ground contact will reduce voltage and increase current confusing the controller even more.
So hunt down the load that is killing your battery first then check your steps out for proper operation. Not sure what the relay you replaced was. Maybe the TV kill switch that will prevent you from watching TV when the coach is going down the road.