Originally Posted by pizzaguy
I saw that in the diagrams.
WHY does a Nav unit need vehicle speed and reverse info? It's a FREAKIN Nav unit - the damn thing KNOWS my speed and direction!!!
(Assuming you know... or have at least a theory, 'cause I don't see it.)
It uses the speed sensor and reverse to accurate determine your speed and direction more accurately while going under bridges, in tunnels and under other obstructions as well as when you're backing up so the car doesn't loose it's sense of "direction"