I am installing an aftermarket stereo and I need to connect to the speed sensor wire, where would I find it and what color is it? 2010 Chrysler Town & country.

If you just pulled the old radio out, and are trying to connect straight to the existing wires, it won't work. You need an interface between your car and the new radio.

Pac-Audio RP4-CH11

http://pac-audio.com/productDetails.aspx?ProductId=1116&CategoryID=26

or

Maestro RR
http://maestro.idatalink.com/product/product/product_id/102

or the Axxess one.