The speed wire is really unnecessary. The accelerometers in the Avic's do a fine job of figuring that out. I never used them, and it was actually a Pioneer tech rep that told me they were a waste of time.

The parking brake you do need, unless your Avic has been modded. My memory isn't all that great, so I don't remember the scoop on the N3. The N1's needed a trace soldered, and I believe the N2's had a switch. I seem to remember some later units needing a pulse box to bypass the brake feature. I'm drawing a complete blank on the D3. Did that one have two slots, one for CD's and one for Nav DVD's? Are you putting the nav disc in the right slot? I'm sure someone will chime on here with the right answers.

In any event, none of these would cause the unit to not recognize the disc. Sounds like you have another issue.

Toby