Ok heres the problem I'm Haveing. My mom drives a 97 lumina and she had me put a radio in it for her. Well the factory radio plug wasnt there so i tracked all the wires down and wired it in to the factory wires. Well the radio works just fine but now the speedo dont work. I've already pulled the radio out checked the wires for anything that looked bad and it all looks good. If you turn the radio up way loud the speedo will jump around, but other then that it dont move. Any idea what the hell I did and how to fix it cause shes bitching at me cause she has a led foot as it is and dont like it not working.

Thanks.