Well, any luck with the steps? I would have expected the steps to retract anytime the coach ignition is turned on, but instead they went out. I thought the controller may have thought the door was open (even though it is closed)....hence check the magnet and door open sensor.
Lets look at what works: the steps function for both in and out......so you have main power and ground OK and the motor is operating. You say the steps follow the door open/closed correctly when the ignition is off and (I assume) the over ride switch is off.
With ignition off; do the steps stay out when the over ride switch is on regardless of if the door is open or closed? The only thing left if all connections at the steps are clean and solid....... perhaps a bad controller; perhaps an abrased/shorting wire causing strange responses? The yellow wire is supposed to have 12vdc on it as well....if not maybe a blown fuse? Perhaps going through a formal test of voltages with a multimeter is required here: Attaching a link to the Kwikee step troubleshooting flow chart.