What does pin 1 do on the docking connector? (iPod won't sync with AVIC-D3)

Question

My wife's 5th Gen iPod stopped working with her AVIC-D3 header in her vehicle. I can connect other iPods of various generations and they work just fine.
This has gone back to Best Buy (its still under extended warranty) five (yes, 5) times and they never fix anything. They do come up with different reasons it doesn't qualify for the "lemon" clause in said warranty - but thats not your problem . So it came back from visit number five and they replaced the battery... nice of them but couldn't find anything else wrong. This time when we took it up there to say "still not working" (so return number six) they were much more accomodating (I just moved to a new city, so I was refreshed to see that customer service isn't entirely dead) and plugged it up to their display stereos and docks there at the Geek Squad station and it worked just fine. They didn't have an AVIC connected - these were all the "two line display" stereos. So in their eyes, its the header (which again, will sync with every other iPod in the world). I brought it home and started looking it over - the first pin in the output socket (pin 1 on the left with the white face up) was simply not there. So I took it back to Best Buy and they said that it was a ground wire and would not impact the player or the way it syncs up.
Depending on which pinout diagram I look at on the web, its either a ground or a firewire pin. While I can't see the ground doing much (but I'm by no means an expert), the firewire is a definate maybe.
So since Best Buy won't help, I thought I'd try to reverse engineer this thing. +If I can figure out if the missing pin is vital, then I can go back (again) and make a case for it.+ Can anyone confirm if this is a ground wire or a firewire pin thats missing (or something else)?
A couple of quick facts:
Its a 5th Generation iPod Video (30GB)
It powers up and charges via the USB cable on a PC and will play if connected to a desktop dock or two line car stereo
If connected, the D3 does not acknowledge it at all
It used to work with this header
While connected, there is no indication in the iPod display that it has external power and I can freely navigate the menus (it normally shows the Pioneer logo)
My iPod Classic works using the same cable with no problem
A friend's iPod 5.5 Generation works fine using the same cable
It is at the latest firmware
I reset it with no change
Any help is appreciated - thanks!

Answer 1

Hello and Welcome to Apple Discussions. 
1. Could you give some specific details of what does and doesn't happen when youy try to sync. Do you have Auto-syncing, or are you manually managing music?
2. You don't need to enter these. Go into Settings > WiFi > and switch WiFi on. Then pick your SSID (network name) from the list that appears. Enter your WEP key/password or WPA password.
The router details etc should be filled in automatically.
cheers
mrtotes