electrical gremlin?

[tiFreak]

ever since I've owned my car, the battery light has been on, but it's so dim that it's not visible in the day and at night I can see it flickering slightly. since the car runs fine I've never bothered checking it out

today I was driving home from class and I noticed my dash lights were dimmer than usual, I tried to turn the knob to the right but it was all the way over so I figured I was just seeing things

all of a sudden my radio shuts off, turns back on, flickers about three times and then stays on, after this happens my ABS light comes on and the battery light goes off. the car still runs fine so I figure I'll just get it home and work it out there. before I get home though, the ABS light goes out and the dash lights turn back up to their full brightness. the battery light never came back on

electrical mods:
-professionally installed aftermarket CD player (one time two years ago I started my car and the CD player didn't power up, restarted the car and it worked fine)

-my interior neons (had them on the whole time and they didn't flicker or anything, they're wired to the back of the 12v socket and I've never had them pop the fuse or anything)

-recently deleted the rear wiper

anyone have any ideas?

[Xenocide]

Is your alternator new?? How many miles are on it?

Do you have a sound system? if so have you upgraded the big three?

With your battery light on sounds like your drawing too much power from the alternator but your battery is able to handle it

[tiFreak]

no sound system, just the headunit, I've never replaced the alternator but I'm looking trough my service history now to see if it was replaced

[Xenocide]

it probably has not been replaced.

Start your car, put your sound system on a pretty loud volume and turn your uber cool neons on. Then measure across your battery terminals with a volt meter and tell us what it says.

When alternators die they stop providing both current and voltage, sounds like you have a low voltage situation, so we can test it with the volt meter, if you wanted to test output current you would need to go to autozone and use their machine. BMW alternators don't seem to last much past 150k in my experience. I would just go ahead and change it out. Autozone sells re manufactured OEM parts with a lifetime warranty for cheaper than new from the dealer.

[cooljess76]

Brendan, check your main engine ground wire. It's located behind your passenger wheel well. You'll need to get under the car and look, but it's connected to the passenger side motor mount and the chassis.

[Xenocide]

yup, with your stereo and neons I would look into upgrading the big 3

[tiFreak]

Originally Posted by Xenocide

it probably has not been replaced.

Start your car, put your sound system on a pretty loud volume and turn your uber cool neons on. Then measure across your battery terminals with a volt meter and tell us what it says.

When alternators die they stop providing both current and voltage, sounds like you have a low voltage situation, so we can test it with the volt meter, if you wanted to test output current you would need to go to autozone and use their machine. BMW alternators don't seem to last much past 150k in my experience. I would just go ahead and change it out. Autozone sells re manufactured OEM parts with a lifetime warranty for cheaper than new from the dealer.

doesn't look like it was replaced, I've got access to all that stuff at work so I'll give that a try tomorrow

Originally Posted by cooljess76

Brendan, check your main engine ground wire. It's located behind your passenger wheel well. You'll need to get under the car and look, but it's connected to the passenger side motor mount and the chassis.

I'll check that too

also, big 3 means alternator, battery and ???

[Xenocide]

big 3 is:

battery to alternator wire
battery to chassis ground wire
engine to chassis ground wire

these wires carry the most current in your car, they will be the bottleneck for anything electrical. You see all these people with huge systems where their lights dim and they think capacitors fix the problem.

If they upgraded the big 3, most of the time a cap would do nothing....but in reality if a cap works, that just means they need a bigger alternator anyways

[tiFreak]

well with the rust up here it probably wouldn't hurt to replace them anyway, might as well upgrade, definitely do it before I get my sub all hooked back up, used to make my headlights dim until it fried the amp

[Xenocide]

sigh, yes, just go ahead and replace your alternator, especially if your putting audio equipment in, get a bigger one if possible, i know the 6cyl can accommodate up to a 120amp alt. Do the big 3 as well, make sure you do it properly with crimped connectors and such.

[tiFreak]

where would I find a bigger alternator? auto parts stores seem to only carry one size for each car

[Xenocide]

try autozone, stock is an 80 amp, looks like bosch make as 90 amp as well. Not sure what you can find that will fit in the stock bracket.

[minicoop900]

e46 318 had 90 and 100 amp, they used the same bracket too so im sure its fit, but good luck finding one :P

[tiFreak]

yeah, I'd probably have to import it for more money than it's worth, I'll just ask all the auto parts stores if they have them in larger sizes, there's a pretty good store that carries parts for European cars that no other stores carry, they'd be my first bet

[thesk8nmidget]

also if none of this does anything i would say your stereo, just because it was "professionally" done does not mean they didnt speed through the install to go take lunch.


you would be surprised how poorly some of our "pro" techs install these units. and most our employees were ex stereo store guys.