Why is my car stereo fuse blowing?

April 13, 2004 1:03 PM

Car stereo fuse blowing extravaganza! Please help salvage my stereo system.

About four years ago my father installed a JVC car stereo in my 1994 Ford Aspire. Two weeks ago I was driving home on a bumpy dirt road and my stereo popped and shut off.

I've needed to replace the fuse twice in the last week - once while driving home (again on the bumpy road) and today after I hit a fairly large pothole.

My question is - where do I start looking? Is this a problem with the stereo itself or the cars' electrical system? Grounding problem? Relation to the bumpy road? Should I start buying fuses in bulk or just stop using the stereo? Google gives me nightmares of fried circuits and junkyard visits. Any help is most appreciated.

Side note - the heater / blower fan also quit on me about two weeks ago, the fuse tested OK, so that is probably the blower motor or resistor. Is this related to the stereo fuse problem?

posted by dual_action to technology (5 comments total)

probably when you go over a bump something is moving, touching metal, and shorting to earth. look at the connections at your speakers and also where the wires leave the stereo. (but i know nothing about car wiring...)
posted by andrew cooke at 1:23 PM on April 13, 2004

Thanks, andrew - I forgot to mention I pulled it out of the dash and checked the wires. Everything looked well-taped, but I don't know much about it either... From what I've read the electrical tape sort of installation isn't the best, so maybe it was hokey to begin with.
posted by dual_action at 1:42 PM on April 13, 2004

I second andrew's suggestion: check the connections on the back of the stereo (sounds like you've done that) and on the backs of the speakers. Make sure that the electrical connections aren't touching anything metal on the car, either.

Some car stereo installations include a separate amplifier, which may be installed elsewhere in the car (for example, the trunk). If you've got something like this, make sure that an empty Pepsi can hasn't rolled over and shorted the connections on the back of the amp, too. It's likely (although not certain) that there will be a bit of discoloration at the location of the short.

As a last resort, buy some extra fuses, turn the stereo on with the car parked, and start banging around the car, attempting to cause the short. Wiggle anything you can reach. You may be able to hear a little "pop" as the short occurs and the fuse blows, which might help you to locate the problem.
posted by Daddio at 5:33 PM on April 13, 2004

Its unlikely that the short has occurred in a part of the car that does not move or come into contact with other things. If you have trunk-mounted speakers, look there first to make sure whatever you put in your trunk didn't sever or smash the wires.

Another thing to consider is that the wires going through the door to the speakers might have finally lost some insulation, and are grounding. This might be easy to detect-- just open the door, peel away the rubber boot that the wires run through, and look for wear.

Many harnesses allow you to disconnect the fronts or the rears (at the stereo, not at the speaker). If you try this, be sure to turn your fader in the appropriate direction. Drive for a week or two, see if the problem goes away, and you've narrowed down your culprits.

If you are totally green, remember this: Fuses blow when the current goes where it's not supposed to; big pieces of metal (your frame or body) have little/no resistance, and thus draw current above what the fuse will permit.

Also, consider taking a $10 Radio Shack meter to each speaker connection (at the back of the stereo), see if the resistances differ markedly.

It's very unlikely that the motor/resistor has anything to do with this problem.
posted by trharlan at 7:49 PM on April 13, 2004

These are all fantastic ideas, thanks everyone! This weekend will certainly be an interesting education.
posted by dual_action at 10:44 PM on April 13, 2004