Thank you, I checked the door switch, wiring for switch, relays etc. it is working properly. I am not sure what else to check only other thing I can think of is the switch hub isn't saying the door is closed.
I had one a few years back (a 2010 model)that did the same thing. I tracked it down to water that had worked it's way into the microswitch on one of the roof hatches. I went through the hatch a day before clearing snow off the roof and some snow must have gotten into the switch. Remember, opening a hatch, side window or rear door can also trigger it.
I'm not 100% sure but I think that is the designed purpose for that system. It want's the driver to walk to the back of the bus and check for students that may have been left on the bus. They usually want you to just open the rear door and close it or there should be a button to press.