05 Touch Screen NAV about to begin install

[89vette]

I have purchased an 05 touch screen NAV non-lux and am about to install in my 05 H2. I found Klaus's install guide and it is great. There are one issue that I cannot verify and I am hoping someone out there has the answer.

It seems I may have to connect a VSS signal to the wire harness in order for the head unit to work properly. I need to know what wire in the harness is the VSS wire because I already might have it. If I have to add it, I need to know what wire on the cluster is the VSS signal.

Thanks and HELP!