danfros

I had my new pioneer Nav radio installed and they can't get seem to find the vss wire. I know it has to be behind the radio somewhere becasue the nav is an option from the factory. Can anyone tell me is the vss wire back there, where and what color? The car came factory with the 6 disk in dash. I guess i will try to hook it up myself but haven't been able to find the info.I think i may also need to know the number of pulses per mile but not sure. Thanks for your time.