vehicle speed sensor wire

I am installing a navigation system in my 01 expedition and i need to know what color is the wire for the vehicle speed sensor. Does anyone know the color of the wire and where it is located or where i might be able to find out the answer to those questions? I have to tap into it so that i can set it up to the navigation computer. Thanks for the help.

Saw your post. I just posted a question about an 03 I have. It did not come with the nav system. Do you know if I can add it anyway? Thanks