just wired a kenwood head unit in to the wifes vauxhall corsa mk2 on an x registration and now the speedo has stopped working, as soon as you put the factory stereo back in it works fine! any ideas on wot would cause this? the only thing that isnt plugged in is the little screen on top of the dash that displays the outside temp and the radio channels! is there another lead that i need or is it cause its a manky griffin! any help or advice is much appriciated!