Car Stereos: copper wire coil sparking, engine whine, fuse holder

Question
I was helping a friend install his new car stereo and when we were done we noticed that the power kept going on and off while checking our wiring we found a coil of copper wire in a plastic housing located on the constant power and it was sparking. I have not come across this in any other stereo i have installed and am wondering what this coil is for and what might be causing the short.

Answer
Hi Chris,

Your wire coil sounds like an in-line noise filter.  Some manufacturers put this on the power wire, while others build it into the head unit chassis.  If necessary, you can cut this out of the circuit, but it's possible that you'll get some engine whine as a result.  A coil definitely shouldn't be sparking, so it certainly sounds like it's defective in any case; removing it might be worth a try.  Sometimes there's a fuse built into the same box as the noise filter; if yours is like this, then you'll want to install a new in-line fuse holder if you cut out the filter box.

Hope this helps!

Brian