Thanks a bunch for the detailed reply. Yeah my 4Runner is on an extended warranty and I don't think this problem is related to either the ipod interface or the SPG any more either. I've returned the truck back to stock nav and reset the zero point calibration in the VSC computer several times and it still throws the code in about a half mile of driving.
The only thing I saw something wrong with in your reply is the assertion that you have to be dead stopped to view video. That must be a later generation thing, but for the VAIS SL2Vi you have a "picture" button on the touch screen much like the address input buttons. while moving, this button is grayed out, unless you switch the SPG to 0-1mph mode, at which time it raises, and you can indeed watch ipod video while driving, as long as the P-brake wire is also grounded.
here's a video of it all working, incase you don't believe me, lol
YouTube - 2004 4Runner Factory Nav Ipod integration
Also, I read every word of your install site for the SPG so I expected less accurate guidance with the SPG installed. I now have terrible guidance with the SPG completely removed. I don't get turn by turn guidance at all and the nav orientation arrow (arrow that represents your position on the map I mean) spins around slowly trying to figure out how you're oriented. Ocassionally the buttons that are supposed to be grayed out will become available for a moment while moving, and it does this WITHOUT activating the SPG switch. It seems somehow related to the fact that I drove the vehicle significant distances with the SPG on so I could test out and then watch ipod videos on the move. The nav doesn't tell me about up coming turns or depict the split screen. Oh and now the auto up down window switch is working but the sun roof is not. It will open but I have to hold it.
I'll read the codes and see what it's saying but I'm going to let the dealer work on it.