Depending on which step you have, there is a controller in the electric lines that reverses the motor to retract/extend the step. You should have 12 volts hot to the controller and a good ground, then there is the door switch which on my coach makes a solid ground, and the open/close wires that tells it what to do. First check to see that you have a good ground and a 12 volt hot wire to the controller, then check to see that the magnetic switch is making a ground. If all seems good, run a hot wire to the motor to see if it is working, if all those check out, you need a controller. The problem usually turns out to be the controller.