Richard,
Finally had time to go thru the diagrams we have. We don't have an 08 Marquis set but the 07 Patriot set includes Marquis and there was very little difference between the 07 and 08 models. That said, the diagrams show a push type switch for sensing the bay door close/open. You should be able to find it somewhere around the door perimeter. It has a plastic plunger, usually white in color.
With all the doors closed, open one and manually push in the plunger while someone monitors the dash indicator. Do this with each door, keeping the others closed. If the indicator goes out, that switch is out of adjustment. Adjust it so it will close sooner.
If that doesn't ID the door, a switch may be faulty. Use the same one open door at a time process but now apply ground to the wire coming out of the end of the switch. (If the switch has 2 wires, just jumper them as one is ground and one is the signal to the light). If the light goes out, you have a faulty switch.
Steve