Yeah, I meant to do that...but the best I can do off the top of my head: it's a light blue wire on the corner of one of the two factory harnesses. I think I remember you having one of the Eclipse nav units, so if you're using an aftermarket wiring harness adapter like the one I've got, then it's a black wire that doesn't get connected to anything. It's fairly accurate (I've noticed +-2mph) when compared to the speedo.

Hope that helps, but I'll definitely snap a shot of it the next time I take the head unit out.

Good luck...