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Weird car electrical problems

Typhoid MannyTyphoid Manny Registered User regular
I'm trying to help my old man work out some electrical problems with his car, an '02 BMW 325i. It goes like this: For maybe five miles after starting the car up, the blinker signals only work intermittently. The turn signals themselves work everytime, but the indicators on the instrument panel won't always light up, or they'll be up to like thirty seconds delayed turning on and off. The beep you get when you leave the key in the ignition and open the driver side door also stays on for a couple minutes after you take the key out and close the door. He took the car out today and said that the lights on the instruments and stereo both got very dim, and when he tried to open the sunroof it wouldn't open. Usually after driving for awhile, things start working normally again

I know a bit about electronics, but very little specific to car electronics. This sounds to me like there isn't enough power to feed all the components asking for it. It doesn't act like a loose connection somewhere and the battery is only about two years old, so process of elimination suggests to my uneducated self that probably the alternator isn't working as hard as it should.

Am I way off base here? Like I said, cars aren't my thing, so it's probably pretty likely that there's something here I'm not considering

from each according to his ability, to each according to his need
hitting hot metal with hammers

Posts

  • knitdanknitdan Registered User regular
    I'm no expert at all but you might want to make sure the ground wire from the battery isn't shorting out. It's usually connected to the frame somewhere close to the battery, and it can get corroded or frayed at the connection to the frame.

    A lot of car repair places will run a computer diagnostic for a reasonable fee. Sometimes they don't even charge one, in hopes that you'll repair the problem there.

    “I was quick when I came in here, I’m twice as quick now”
    -Indiana Solo, runner of blades
  • Reverend_ChaosReverend_Chaos Suit Up! Spokane WARegistered User regular
    I just dropped nearly $1400 to get an electrical problem fixed in my vehicle. I am no expert, but I would do as knitdan says and at least take a look at the ground wire. Check it from the battery to wherever it goes. If the ground is shorting out, or has a bad connection, you will lose power. If the connection is covered in a white powder-like substance that could be the problem. Get it cleaned up. It could also be a problem with the alternator not charging the battery correctly, or it could be an old battery.

    If that isn't the issue I would call around to some local shops and see if anyone does free diagnostics, or some might waive the diagnostic fee if you fix the issue through them.

    “Think of me like Yoda, but instead of being little and green I wear suits and I'm awesome. I'm your bro—I'm Broda!”
  • BlazeFireBlazeFire Registered User regular
    edited June 2014
    Just an FYI, a ground cable can't short out. Cables short out when they are carrying voltage and short-circuit to ground.

    A ground cable CAN have a loose connection though and that is a great thing to check first.

    Do you own a multimeter/voltmeter? Connect it to the battery and start the car. The voltage should be ~14 to 14.5 V. If lower, the alternator is where you want to start investigating.

    If the voltage is okay, start pulling fuses for non-critical things like lights and see what happens.

    BlazeFire on
  • ThroThro pgroome@penny-arcade.com Registered User regular
    The turn signal indicators still lighting up, but being delayed or sometimes not working sounds like the capacitor in that circuit is bad (assuming that's how it's wired in an '02).
    Taking the key out and stuff still drawing power also sounds like a capacitor not draining properly, or as others have mentioned a bad connection to ground from the battery (though Blaze's terminology correction is correct).

  • Donovan PuppyfuckerDonovan Puppyfucker A dagger in the dark is worth a thousand swords in the morningRegistered User regular
    Is the ignition switch fucked? Not the key barrel, but the actual set of rotating contacts connected to the end of the barrel.

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