with the battery bulb in, car wont stop

what gives...

was replacing some bulbs in thedash of my 1981 500 sel that is converted to a 300d

so when i put in the new bulb in hte battery indicator light in the instrumnet cluster, start the car and then turn the key off, IT WONT STOP??

so i take the buld bout, turn off the key and it stops.

i tey it a few times and same thing.

when the buld is in the little brown housing in the instrument cluster and i turn off the key and even take it out of the barrell the car wont stop.

any ideas folks?