Car electric issue due to cold weather

Question

I live in the UK and lately is being quite cold. I've seen this question to see common problems related to a cold weather. This morning however something weird happened. I own a peugeot 206, and it happened that I forgot to turn off the radio, which is usually ok (so far) because when I turn off the engine the radio turns off automatically, but when I start the engine again the radio turns on together with the engine.

This time instead happened that I turned on the engine and the radio turned on as well (usual) but I couldn't turn off the radio using the radio button that would turn the radio on and off while the car is running, also it took a while to turn off the radio even if the I turn off the engine.

This thing make me wonder if the battery could die while I'm far away from the car, which would be of course annoying...

Why did this happen? What would you suggest to do in such a case? (other than probably pay more attention and turning off the radio before I shut down the engine).

Thank you

Answer 1

Car stereos, like most other electric components of your car, need 12v from the battery to run. Most modern stereos I've seen get 12v continuously from the battery, which allows them to enter a low power consumption mode when the car is off. They can use enough power to keep things like the clock and your radio presets stored, but not enough to have a significant affect on the battery. Generally this wire is yellow.

Stereos also use a separate signal wire that tells them when the car is ON or in ACCESSORY mode. When the stereo gets 12v on the signal wire, the stereo knows it's time to turn on and start playing music, as someone is in the car wanting to use it. Likewise, when the signal stops, the car has been turned off and the stereo follows suit. This wire is likely red.

It's worth noting on some modern cars this behaviour can vary. Sometimes the stereo continues to play until the keys are removed, the door is opened, or some set amount of time passes. You should also note that wire colours can vary. You'd have to check a wiring diagram for your car and your stereo to know for sure.

While it's possible the wiring or car ignition has become damaged, the fact that you can't turn the stereo off with the power button suggests to me that it's a problem with the stereo unit itself. You can get a voltmeter and check the wiring, or try a second stereo if you have one and see if there is a difference.

Like you said, it's probably best to keep an eye on it every time you turn off the car until it gets sorted out.

Answer 2

The fact you can't turn the stereo on/off with the button suggests the button is broken. Possibly contact corrosion because you never use the button. Try pressing the button 20 times, see if that improves matters.