If itís a version of the Kwikee steps, there should be a test procedure in the back of the manual. You should be able to find it from the Thor owner site or elsewhere online (using the model number found on the label, Google is your friend here) if itís not with your other RV documentation.
In my case, my steps decided to start extending when the ignition was on instead of retracting for some reason. I wound up bringing the steps in, disconnecting the plug underneath the rig and zip-tying up the cables to get it home whereupon I went through the testing procedure and found the controller was faulty. It was a really easy swap-out if youíre somewhat handy with tools. For good measure, I also ran the ground to an existing frame ground because it was just tied to the aluminum box surrounding the fixed stairs inside. Itís been running like a champ ever since.