Strange Electrical Happening with My Car and Two Car Stereos

January 29, 2005 12:23 PM

Apologies for CarFilter, however: some weeks ago my car stereo began behaving badly before finally dying. [mi]

I fired up the ignition after work one day and my car cd player came on just fine for a bit, but after a moment or two the volume suddenly shot all the way up to maximum and wouldn't turn down no matter how frantically I assaulted the controls. I was finally able to get it to shut off by holding the power button down as hard as I possibly could. when I got home that night, I unhooked the battery for a bit and then reconnected it and everything seemed to work ok but the next day the very same thing happened again only this time the player wouldn't power back on when I reconnected the battery.

I dusted off my old tape player and installed it in my cd player's place and the backlight for the screen would come on but no sound would come out. so finally I just straight up bought a new cd player and installed it but it won't power on at all. I've replaced the fuses and made sure the correct wires were wired together and yet! I suspect there may be some strange electrical issue I haven't considered as the temperature gauge and odometers are also out. I had to replace my alternator earlier last year and ever since none of my dials and guages have really worked right.

my apologies again for carfilter but I am a very, very indebted student and I'm weary of mechanics! and riding around in total silence is a real bummer!

posted by mcsweetie to technology (5 comments total)

That is really, truly strange.

One possibility is a bad ground somewhere. First, make sure that all connections at the battery are clean and tight. I doubt that'll fix your problem, but it makes sense to start there.

You need to see, then, if your stereo has 12v, and if your stereo's ground is working. Do you have a meter? Can you get one? If so, I will explain to you how to do this.
posted by trharlan at 1:30 PM on January 29, 2005

This could be as simple as a wire on the harness wrong. First, pull the plug, read the instructions a few dozen times and reinstall the stereo. That's probably not going to work though.

"...considered as the temperature gauge and odometers are also out.

For me, and do consider that I'm totally baffled by automotive electrical sytems, this is the key.

My guess would be that the voltage regulation isn't correct. You say that the electrical issues started when you replaced the alternator -- it's entirely possible that the alternator is spitting out too much juice that isn't being regulated properly.

Are fuses blowing?

You don't mention what kind of car it is, but modern electrical systems are complex and it seems that your problems extend beyond the stereo. I know you don't want to hear this, but best your bet is going to be a professional with the specs and the meter to debug this. Unless your driving an '82 Malibu your going to need someone who knows what they're doing.

Maybe returning the new stereo and buying one from a shop that does their own installs might save you a few bucks. You'll pay more, but part of the cost will be absorbed by their markup on the components and hopefully they'll troubleshoot the electrical system in the process.
posted by cedar at 2:18 PM on January 29, 2005

I had a similar thing happen on my pioneer DEH-P41 stereo. It turned out the volume microswitch was dirty. Luckily the faceplate is removeable, so I didn't have to abuse the thing to turn it off. :-)
posted by shepd at 2:41 PM on January 29, 2005

I'd be betting, as cedar does, that it's noise in the electrical system. Either a bad ground, a faulty regulator, or a bad diode in the rectifier pack.

Depending on the age, it might even be the ignition - I had an old Toyota with points ignition that used to cause electrical havoc when the points wore, well before the car started running badly.

Any way you look at it, get thee to an auto electrician! Finding a good one is left as an exercise for the reader, because that in itself can be a Sisyphean task.
posted by Pinback at 4:52 PM on January 29, 2005

My last car had the stereo go wonk like that. Turned out the problem was one of the speaker lines was shorting, and the amp block was being very unhappy at the 0 Ohm impedance this presented to it.

I didn't blow the amp, which is surprising.
posted by eriko at 6:16 PM on January 29, 2005