On my 03 montana , under the light switch is a dimmer switch , just rotate the dimmer switch all the way, one way will dim the dash lights and the other way will brighten up the dash lights then if you keep rotating it , you will light up all interier lights. However I have a overide switch on my over head consol that will kill all interior lights I use it if the kids are constally going in and out of the van or I am loading it up . Maybe you have the overide switch enabled ?