Originally Posted by Kipp
that is correct that you would lose those features, if the car has them in the first place. if all he has is the basic audio system then it's not really needed though. the data signal to the headunit is just for the accesory. speed sense doesn't work on aftermarket headunits unless it's a nav unit and even the newer ones of those don't need a speed sense input to work correctly like the older units did. dimmer is usually a seperate wire that is voltage based and also doesn't usually work properly with aftermarket units.
Ok, good deal! Thanks Kipp for clearing that up for me(=