Re: 05 navigator door step
your door and power running boards are linked..it sounds like the sensor/latch that is the problem and not the boards, its not sensing the door is close. search on related topics in this forum to find a solution that might help. Some have used simple methods to correct the "door ajar" light.
If nothing works email me and I can send you some service manuals guides for the door/latch. It would be about removal, inspection and such.