Two fairly common causes of the Kwikee steps not extending or retracting. One, it could be the magnetic sensor in the door frame not sensing the door is open or closed. This usually causes the steps to not retract. Testing for this is simple - take a strong magnet and bring it in close proximity with the sensor in the door frame. If the steps retract then this is most likely the issue and either replacing the sensor, the magnet in the door or adjusting the sensor placement solves the problem. (If the gap between the door magnet and the sensor is to large the sensor won't detect door closed. This can happen as the door gets a bit mis-aligned due to vehicle vibration, etc. My fix is to just place a garden hose washer behind the sensor so it protrudes a bit more.)
Second, for the steps no extending. The motor used in the steps can develop a flat spot on the armature from vehicle vibration while traveling down the road. In this case the motor needs to be replaced. One simple test of this is to rap on the step motor a bit to see if it "wakes up" and the steps extend. BE CAREFUL DOING THIS! Watch where to put your arms, hands and fingers while doing this as you can loose body parts if they're in the wrong place when the steps decide to work.