If not, then it is greyed out while you drive because Pioneer has put blocks on certain features unless the parking brake is engaged. They (along with most nav system makers) had to do this in order to avoid many lawsuits from people who got into accidents while using their nav system.
All the units has a bypass to these blocks that is fairly easy to do. Check the forum and go to Hacks/Mods underneath the name of the unit you own.
Yes, I have bypassed the unit. Just to double-check, it is still greyed out with the parking brake engaged, not that it should matter with the bypass. Any other thoughts?