I have an aftermarket head unit in my 2014 Jetta that I installed myself. After several times waking up to a dead battery when I was sure I didn't leave the radio on, I decided to kill all power to it when the ignition is off.
There are, of course, two power wires coming from the wiring harness. The yellow one is labelled "12v battery / constant", and the red one is labelled "12v ignition / switched". The head unit also has two wires for power, but I wired them both to the red wire anyway to make sure it didn't get any power with the car off.
After another dead battery and then verifying that the radio does indeed continue playing with the car off, I took a volt meter to it and confirmed: the yellow and red wires each give 12.5 volts regardless of if the car is on or off. How can I resolve this?