A few of our 10'-11' C2's have some sort of issue with the stepwell light. If the door is open with the bus running the light will not come on and acts as if it's blown out, but when you hit the reset button at the back of the bus, or switch on the dome lights it will come on. The bulbs have been replaced by other bulbs, and still no luck.
If it comes on with the dome lights or by other means, I would assume it is not the microswitch. Might have been programmed to come on with dome lights? May need a parameter changed. You can order a C2 with the stepwell light coming on with any of the following circumstances: 1. door open and parking/headlamps on 2. ignition in IGN or ACC and door open 3. ignition in IGN or ACC and dome lights on 4. ignition in IGN or ACC and dome lights on OR door open 5. ignition is "on" and door open and marker lights on