Old thread BUT this happened to me today... still not fixed 4095 mountain air DP all was good... except left taillight bulb... went to replace it bulb came apart in the socket.. no big deal it came out (maybe shorted it?) new bulb and now no tail or running lights turn and brake are good... 2001 has 3 fuse boxes in front above the genset.. NONE of the fuses are marked tail light... inside top dash fuse box no tail light fuse... I think i checked (pulled and looked at every fuse) and nada.... someone said there is a fuse in a fuse holder near the rear master switch? i have never seen it but? is it there and where in the heck is the tail light fuse in the front? thanks for any help... some old threads need to be kept alive there are no "new problems" just problems you haven't had YET