My understanding is that "RTFM" is particularly nasty remark reserved for true a**ho*es and imbeciles. ...Or maybe your reply was an innocuous suggestion? however, I prefaced my previous post with the fact that I did RTFM. Granted I may have overlooked the pertinent information, so I have looked it over a few more times. Still I find nothing. I installed it without connecting that wire.
only reason you'd need the dimmer wire is if that display is too bright at night, and you find it distracting while driving. otherwise, you're good to go.