I recently did the conversion with the wire for the N4 and now I have no speed control and the location indicator constantly needs to be modified. Anyone expericencing this?

No. Check your antenna reception and that the VSS wire is hooked up

yeah, agree with whtcr, sounds like vss and antenna not connected, if you ever have to modify your location more then 20 feet on the map that usually indicates your antenna is not connected. Go to menu, setting, hardware info and it should give you the readings, drive around and see what it says for ant reception and vss.