GPS speed sense

I'm putting the Eclipse AVN2210p into my 06 aveo. http://www.eclipse-web.com/avn/avn2210poverviews.html

I've got all the wiring harnesses, kits and what not. Should be a super simple job. But I don't know where to tap the speed sense cable for the GPS into the car.
Haven't opened the dash up yet, but I don't want to be fiddlding around with the wires if I don't need to.

Can someone tell me which wire i need to tap into for the speed sense function on the aveo or who I might need to contact to determine this?

Thanks so much. I'll be sure to post pictures of my rad new unit.

on my nav 101 unit the GPS does the speed sense for me. it tracks were im at, then again and maps that out and vola, the speed

^^^^Yeah the GPS function should calculate your speed. Are you sure you need that connection?

It's called dead reckoning, found on higher end units. If you lose satellite reception, it'll keep on navigating by assuming you're taking the correct turns, but using the speed sensor to calculate distance travelled, distance to turns etc etc. Once satellite reception comes back, it'll reevaluate position etc.

Dead reckoning is how the old mariners plotted a course before electronic navigational aids....So is it needed? When the GPS regains signal, bam you know where you are.

I should have put quotes around "dead reckoning" so it isn't misinterpreted. It's a term used by Garmin and perhaps even Magellan and TomTom to describe the feature on GPS units that have it. Is it necessary? Probably not... but if you drive a lot of valleys in mountainous regions, it may be useful.

FWIW, I always lose satellite reception in the Ville St.Marie tunnel under downtown Montreal, which sucks because of all the convoluted secondary and tertiary exits, that by the time the GPS finds the satellites again after I take an exit to leave the tunnel, I have to rely on "standard navigation" choose the proper 2ndary exit, which isn't always clearly marked. "Dead Reckoning" would help in that case...

Dead reckoning is a nice feature for when you are in the mountains, however, it is not required for your GPS system to work properly. It will get a track on you once you leave the tree, mountain cover, or the tunnel.
It is nice to have though. I would say if you don't want to fool with it, don't, if you don't mind doing it, go ahead. It is really up to you.