Thanks guys.
The Satnav is Nurrish's custom jobby. Which reminds me - Nurrish I've plugged the RCA cables off the Satnav into the headunit audio L+R inputs and the yellow one into the ext video in. For some reason it doesnt seem to want to come out on the Headunit, even just the sound. Any ideas? Maybe I need to have a bit of a play around with it.
What are you trying to do buddy?