I have a 2008 volkswagon rabbit. The sound system has stopped working completely. I've checked the fuses and none of them are blown. It is a stock 2008 vw rabbit 4 door which came with the upgraded sound system option. I did not add any sound system components to it at all.

This sound system issue didnt happen randomly. I woke up one morning to my car battery dead. I went to jump the car and actually i placed the jumper cables in the wrong order. Meaning i made a closed loop between the two batteries (DOHH!). I hooked the negative on my battery to the positive on the other guys car battery. I guess this is what happens after being in a rush.

Anyways i went to start the car (with the batteries hooked up incorrectly). I actually did turn the key maybe 2 times then realized i was gonna melt the battery if i kept trying. Some observations when trying to start the car with the cables hooked up incorrectly:

  1. the car did not respond at all when turning the key. It seemed to have zero power which makes sense i closed the circuit between the two batteries.
  2. When i went to grab the jumper cables to disconnect them they were very hot.

After reconnecting the cables the correct way my car started with no problems. The only issue was that i had no sound system. Not even a flicker and it still has never turned on since. There does not seem to be any problems with anything else in my car. all lights turn on fine.

This is what brought me to test the fuses but none of them were blown. I'm curious is it still a possibility that there is now a melted ground wire somewhere even without a blown fuse? How about did i damage the sound system? Melted some other wire? Any tips?

Car: 2008 VW Rabbit 4-Door.



  • 1
    Some head units have small fuses within the unit itself, typically in the form of a mini-blade fuse pushed into the rear of the unit. Have you checked for this type of fuse or only the condition of fuses in the two fuse boxes? Dec 31, 2018 at 8:54
  • @Steve Matthews When I took the car into my dealer, they mentioned the fuse was inside the head unit itself. They had to remove the head unit using a "special tool" then it was fixed.
    – Dr. Dan
    Jan 4, 2019 at 21:14

1 Answer 1


My guess is it's fried. When you hook two batteries up in series (as you did), the resulting voltage is the sum of the battery voltages, so for a few seconds you had a 24V electrical system. I'm surprised the ECU didn't fall over as well, but perhaps it's better protected.

Have you tried entering the unlock code? In my Audi, after I unhook the battery (or it goes dead), my radio displays "CODE", meaning you have to enter the anti-theft code. Could it be that yours doesn't display anything, but just waits for you to enter it? Check your owner's manual. Hope it's something like that, instead of being broken!

  • Yeah, I'm hoping I didn’t fry my friend's mom's car he was taking care of too! woops! Thanks @TMN I will test this out and let you know. Crossing fingers about the unlock code.
    – Dr. Dan
    Jun 4, 2014 at 17:55
  • If the OP switched the cables, the batteries weren't in series with the rest of the car, they were in a loop. That's a 24V short circuit, not a "24V electrical system".
    – user253751
    Jan 6, 2016 at 2:44
  • The car would still see either +12V or -12V since it is connected between the two batteries. This will nicely charge the battery very quickly, and potentially lead to an explosion or, at least, melted jumper cables. Connecting two batteries in a series loop turns the cables into a pair of resistors, with effectively zero (relatively speaking) resistance. The cables get hot, as they're carrying an immense amount of current.(V = I*R, where R -> 0, and V is constant, sends I -> INF.) In any case, no component in the car will see 24V.
    – 3Dave
    Apr 4, 2018 at 18:33

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