Lights flickering at idle (engine, replacing, Chevrolet, battery)
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No idea if this is your problem or not, but my Scirocco was doing that awhile back, it turns out that the voltage regulator, held to the alternator by 2 screws, was loose, one screw had fallen out and the other one was loose.
No, I wasn't smart enough to find the problem at this stage, I kept driving it with the flickering lights till the 2nd screw fell out as well, which of course made the alternator go to max output...
fortunately I was close to home, was able to figure out what happened and unplug the alternator entirely, drive home on just the battery...
So, if your alternator has an "onboard" regulator, take a look at the regulator's mounting screws...
One thing is certain, if you don't find the problem at this stage, Mr. Murphy will make it more obvious for you, normally at a rather inconvenient time..
normal operating condition
clean your throttle body with some carb cleaner and an old toothbrush
you can upgrade to a larger CCA battery and a higher output alternator, but the harness can only handle so much power anyways
Sounds like it's idling slow enough that the alt doesn't know if it wants to put out or not. If you pick up engine speed about 100 RPM does the problem stop?
This can be due to many possible factors, including a bad voltage regulator, an alternator that's not in good condition (possible bad diode, bad rotor/stator, poor internal connections), poor/high resistant charging system connections, poor/high resistant grounds, and also the idle surging is enough to cycle the alternator in/out of the charging system.
System voltage may not capture the fault. You need to check the wiring system wiring and connections for voltage drops (high resistant connections) with the voltmeter, or use a o'scope to capture the alternator voltage fluctuations that a voltmeter won't reveal.
If you aren't familiar with these types of tests, or don't have the equipment, then you'll need to take the car to an automotive electrical shop ... one that actually can test for the faults, as opposed to many shops that will simply start replacing parts.
Another vote for a bad vr. Had one go bad on an alternator once....yes the alternator worked but the volts would increase and decrease with engine rpm speed....as a result the lights would get brighter and dimmer.
Sounds like it's idling slow enough that the alt doesn't know if it wants to put out or not. If you pick up engine speed about 100 RPM does the problem stop?
Yes if you pick up idle speed the flickering seems to go away...or possibly the frequency increases to the point that you don't notice it.
This can be due to many possible factors, including a bad voltage regulator, an alternator that's not in good condition (possible bad diode, bad rotor/stator, poor internal connections), poor/high resistant charging system connections, poor/high resistant grounds, and also the idle surging is enough to cycle the alternator in/out of the charging system.
System voltage may not capture the fault. You need to check the wiring system wiring and connections for voltage drops (high resistant connections) with the voltmeter, or use a o'scope to capture the alternator voltage fluctuations that a voltmeter won't reveal.
If you aren't familiar with these types of tests, or don't have the equipment, then you'll need to take the car to an automotive electrical shop ... one that actually can test for the faults, as opposed to many shops that will simply start replacing parts.
I agree with Mitch... usually the voltage regulator causes this.
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