How do I make an after market stereo switch off when my car is off. I have an Audi A3 and Ive tried the switch the yellow and red wire and it stays on still. This is starting to kill my battery! Pls Help.
Audis dont have an ignition feed on the plug behind the radio you need to get a multimeter and look for a 12 v when you turn the ignition on you will find this either on the side of the dashboard behind a panel or in the footwell up above the accelerator pedal and you will need to run a wire from one of these positions up to the radio and then either plug it in to the red or yellow wire which ever one has no permanent 12v going to it
hope this helps