Hi Ryan, Thanks very much for the reply. The harness I bought is the amplifier bypass one. Sadly upon trying the normal ford adaptor (think this is called the ISO lead..??) the radio just comes on without any sound at all (not even from the tweeters). I noticed there's another ISO plug and connector further behind the dash but this was connected to the plug I tried connecting to the normal ford adaptor. One thing I found odd is that there is only one connector from the Sierra Harness although two sockets for the ford adaptor (one brown/one black - the black one is the one I could connect to). Any other suggestions would be great otherwise its off to my local car audio chap.... Thanks very much