what is the min needed to be hooked up for the nav to work correctly?

Nav antenna and VSS wire

^ you don't NEED the VSS wire for it to work. It just helps keep it accurate.

What you need to have hooked up for it to work:

Both power wires

Ground wire

Speakers (either using the speaker wires or RCA outputs and external amp)

GPS antenna

Parking brake wire (to parking brake switch for normal installation, or just grounded for a bypass installation)

Mute wire (grounded, only necessary if doing the bypass)

thank you guys, ive had it all hooked up for a bit, but didnt want to tackle the vss wire yet, i read different things about needing the vss wire hooked up or not

What type of car is it?

I have an '07 VW and I found that purchasing the most complete wiring harness for my car made the installation a piece of cake and completely eliminated the need to make those kinds of decisions. I hooked up all of the wires that the D3 uses for installation and I won't have to go back into the dash again.

If you can find (and are willing to spend the money) a complete wiring harness I would go that way.

Just my 2 cents.

its a 00 explorer i had a pioneer in there to start with, so i took the ebrake wire out of new harness and put it in the old the speed install i have it working now, later this summer when i get some time off i'll redo it all and add the vss