03 rs6 interior lights issues and more - please help !

For some reason something in the cluster or something keeps shorting out fuse number 15 it causes the voltmeter not to work the battery The battery icon in display word fuse over odometer, back lights , all interior switchgear do not work in involves dimmer switch. At first I noticed that the interior back lights were not working they were very dim and I wiggled the dimmer knob next to the headlight switch the lights on the switches for the AC unit , window switches heated seat nubs etc. would come on normally very briefly I thought it was a problem with the dimmer switch since I've proven that's fine after a while the tail lights would not show it all the radio button still laid up but did not dim with the knob but the dashboard does work then I got a new error message with the yellow icon it blows fuse 15 --- i'm stuck does anyone here I think it's the body control module I don't think our cars have an light control module , maybe a comfort control module ???? anybody have any info - please Thank you ahead of time. Oh yeah I also swapped out the cluster but I couldn't code it to the car since I didn't have the tools I was able to swap back to the old cluster and get the car running again when I plugged the new cluster in the voltmeter at work but the light still did not light up that's all I have to add. Thanks again for all the advice ahead. I am leaning towards the body control module or the comfort control module what do you people think