It sounds like your accessory power wire from the car isn't working, yes? You could check the fuse on it. Also use a test light or multimeter on the accessory wire with the car on and see if you have your 12 volts. Obviously if your ACC/IGN fuse is fine and you have no voltage at the wire something went wrong. If thats the case I'd just run a new wire back to the fuse box or some sorts. Or if your lighter socket is only active with the car on. The turn on for the radio uses next to no power, so you should be able to splice it on to whatever will work for you. Otherwise relays!
WHOOPS LOOKS LIKE AN OLD THREAD. |: