# lights dim/flicker while idle.... voltage regulator???



## VW Jenno (Jan 19, 2011)

hey guys,

i have 05 vw golf, my interior and exterior lights have been dimming or flickering while im idle. when i'm driving the lights seem fine alos when i hit the gas to start driving or rev my car theres a whining noise, i'm thinking they're connected somehow but not really sure. the car hasnt stalled on me at all and hopefully it won't. my mechanic said it could be a faulty voltage regulator. any thoughts on what it could be??? :what:

thanks Jenn


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## NFrazier (Jul 22, 2006)

VW Jenno said:


> hey guys,
> 
> i have 05 vw golf, my interior and exterior lights have been dimming or flickering while im idle. when i'm driving the lights seem fine alos when i hit the gas to start driving or rev my car theres a whining noise, i'm thinking they're connected somehow but not really sure. the car hasnt stalled on me at all and hopefully it won't. my mechanic said it could be a faulty voltage regulator. any thoughts on what it could be??? :what:
> 
> thanks Jenn


Well the lights will dim momentarily when you use your power windows or when the SAI pump turns on.

As far as the whining noise goes, do you have an aftermarket or factory radio? Is it coming from the speakers or the car itself (somewhere)?

If it is coming from the speakers, is it from all of them or an individual speaker/speakers?

If it is from 1 or 2 speakers then you could have an issue with a faulty speaker(s), if it is coming from all of the speakers you could have an issue with a faulty ground on the radio (also known as a ground loop).


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## VW Jenno (Jan 19, 2011)

yes the lights usually dim for a second when i use the windows, but this is while i'm at idle using nothign just sitting in my car. this morning while i was sitting the lights all turned off for a split second and came back on. 

i have stock stereo, the noise seems to be coming from under the hood somewhere, i cant really pin point it :/


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## NFrazier (Jul 22, 2006)

VW Jenno said:


> yes the lights usually dim for a second when i use the windows, but this is while i'm at idle using nothign just sitting in my car. this morning while i was sitting the lights all turned off for a split second and came back on.
> 
> i have stock stereo, the noise seems to be coming from under the hood somewhere, i cant really pin point it :/


Is the whining noise constant or intermittent?

Is it just the headlights? or interior lights as well?


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## VW Jenno (Jan 19, 2011)

NFrazier said:


> Is the whining noise constant or intermittent?
> 
> Is it just the headlights? or interior lights as well?




noise is constant, when i am accelerating it gets louder then evens out to a consistant noise. wehn i am stopped you can hear it a little bit.

both interior and exterior and all dim at the same pace.


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## NFrazier (Jul 22, 2006)

VW Jenno said:


> noise is constant, when i am accelerating it gets louder then evens out to a consistant noise. wehn i am stopped you can hear it a little bit.
> 
> both interior and exterior and all dim at the same pace.


First and foremost I'd check the battery grounds.

The whining noise is hard. It seems turbo related until you said you can still hear it when you stop. Maybe injectors or a boost leak?

Do you have any modifications done to your car? Boost gauge, etc?

I'd check the pcv hosing, did anything spark this noise?


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## VW Jenno (Jan 19, 2011)

NFrazier said:


> First and foremost I'd check the battery grounds.
> 
> The whining noise is hard. It seems turbo related until you said you can still hear it when you stop. Maybe injectors or a boost leak?
> 
> ...




the car is completely stock, i have not done a thing to it. 

i also thought maybe it was a leak but the noise seems to only be around when the lights are going in and out of dimming.

the lights first started dimming a few weeks ago when it was raining so i thought maybe the alternator just got wet and when it dried everything would be fine. and it did go away for a little bit. then one night driving the lights started dimming when i was at a red light. and now its fine when i first start the car but after i've been driving for awhile the lights dim and flicker when idle, and when i'm actually driving the light are completely fine. the timing it does this is crazy and i cant seem to figure out what the problem is. i've had the alternator, battery and fuses all checked and everything came out normal.


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## NFrazier (Jul 22, 2006)

VW Jenno said:


> the car is completely stock, i have not done a thing to it.
> 
> i also thought maybe it was a leak but the noise seems to only be around when the lights are going in and out of dimming.
> 
> the lights first started dimming a few weeks ago when it was raining so i thought maybe the alternator just got wet and when it dried everything would be fine. and it did go away for a little bit. then one night driving the lights started dimming when i was at a red light. and now its fine when i first start the car but after i've been driving for awhile the lights dim and flicker when idle, and when i'm actually driving the light are completely fine. the timing it does this is crazy and i cant seem to figure out what the problem is. i've had the alternator, battery and fuses all checked and everything came out normal.


if the noise is happening at the same time it sounds like either a secondary air pump issues since it will turn on randomly to adjust the emissions of the vehicle, especially at idle.


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## BassNotes (Mar 16, 2005)

Unless you like to empty your wallet unnecessarily, check the electrical connections before replacing the voltage regulator or anything else. 

Check the ground connections at the chassis (under the battery tray) and on the engine (at the tranny bellhousing). Check the - battery post connection too.

Also check the + alternator lead and all the connections on the fuse panel above the battery. If the post terminal where the alternator lead connects gets hot when the engine is running, that's a common problem spot.

"Check" means:


Measure DC voltage across the connections with the engine running and headlights and other electrical accessories running. You should measure less than 0.1 V between any two of these points: the engine block or alternator body; the chassis; and the - battery post (not the clamp terminal on it). You should also measure less than 0.1V between the alternator lead (stick the point of the voltmeter probe right into the wire) and the + battery post.
Take apart the ground connections, scrape or wire brush away any corrosion, dab some dielectric grease, if you have some, on the mating surfaces, and reassemble them securely.
Not relying on the "eyeball ohmmeter."


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## VW Jenno (Jan 19, 2011)

thank you guys for trying to help me figure it out! i've been going crazy the passed few weeks:what: 

but i finally gave in and took it to my mechanic today.... he said it might be the alternator voltage or the ignition coils, since they like to go crazy as well, but either way i trust him 100% on whatever he thinks the problem is. i should find out whats going on in the next day or 2 . i'll update once i know more.


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## BassNotes (Mar 16, 2005)

Did he actually mention ignition coils as a possible cause? Does he know much about electricity?


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## VW Jenno (Jan 19, 2011)

BassNotes said:


> Did he actually mention ignition coils as a possible cause? Does he know much about electricity?



yes he did, he loves working on german cars said the last time he had a car doing similar things it needed the coils changed out, but he also said that might not be the case with my car, he's good with electric so i'll find out today whats going on


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## BassNotes (Mar 16, 2005)

Well, good luck, but I think either he's not that great with electrical stuff or you misunderstood what he said about ignition coils.


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## NFrazier (Jul 22, 2006)

BassNotes said:


> Well, good luck, but I think either he's not that great with electrical stuff or you misunderstood what he said about ignition coils.


:thumbup:


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## Dr. Ew (Sep 24, 2007)

NFrazier said:


> Well the lights will dim momentarily when you use your power windows or when the SAI pump turns on.


I recently picked up a mk4 gti and I noticed this the other day, is that normal? I dont remember this happening with any of my previous cars.


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## ttocsybles (Sep 7, 2006)

> hey guys,
> 
> i have 05 vw golf, my interior and exterior lights have been dimming or flickering while im idle. when i'm driving the lights seem fine alos when i hit the gas to start driving or rev my car theres a whining noise, i'm thinking they're connected somehow but not really sure. the car hasnt stalled on me at all and hopefully it won't. my mechanic said it could be a faulty voltage regulator. any thoughts on what it could be???
> 
> thanks Jenn


the grounds are difinatly a possibility but, I think you hit the nail on the head with the first post. Voltage Regulator! lights dimming/flickering at idle is a symptom of a bad alternator (or internally, the voltage regulator). alternators will put out 12.5-13.5 VDC at any speed while operating, but the amperage is much lower at idle. as the engine RPMs increase, so will the amperage output from the alternator. I guess where I'm going with this the voltage regulator turns the AC power created by the alternator into the DC power that everything in the car run on. a faulty/failing voltage regulator will allow AC current to pass through when DC current is low (at idle). and if you know anything about electrical power/electronics, things designed to run on DC don't like AC. 

The whine, could have very possibly been coming from the radio/speakers, again back to the alternator putting out AC current which could then be induced into surrounding wires. 

If your mech replaces the alternator ask him to do a capacitance check and an amperage check on the battery.


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## BassNotes (Mar 16, 2005)

ttocsybles said:


> the grounds are difinatly a possibility but, I think you hit the nail on the head with the first post. Voltage Regulator! lights dimming/flickering at idle is a symptom of a bad alternator (or internally, the voltage regulator). alternators will put out 12.5-13.5 VDC at any speed while operating, but the amperage is much lower at idle. as the engine RPMs increase, so will the amperage output from the alternator. I guess where I'm going with this the voltage regulator turns the AC power created by the alternator into the DC power that everything in the car run on. a faulty/failing voltage regulator will allow AC current to pass through when DC current is low (at idle). and if you know anything about electrical power/electronics, things designed to run on DC don't like AC.
> 
> The whine, could have very possibly been coming from the radio/speakers, again back to the alternator putting out AC current which could then be induced into surrounding wires.
> 
> If your mech replaces the alternator ask him to do a capacitance check and an amperage check on the battery.


If you even suspect a voltage regulator is faulty, you might as well make sure the electrical connections are good first. Otherwise you might spend a wad of cash fixing the part of the electrical circuit that isn't actually broken.

The current (or "amperage," as you call it) put out by the alternator depends on the output voltage and the load on it. A defective alternator might have excessive ripple or whine on its output DC, but it would have to fail in an almost certainly impossible way (with certain diodes failing open and other failing as shorts) to put out AC.

What is a "capacitance check"?


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## ttocsybles (Sep 7, 2006)

> If you even suspect a voltage regulator is faulty, you might as well make sure the electrical connections are good first. Otherwise you might spend a wad of cash fixing the part of the electrical circuit that isn't actually broken.
> 
> The current (or "amperage," as you call it) put out by the alternator depends on the output voltage and the load on it. A defective alternator might have excessive ripple or whine on its output DC, but it would have to fail in an almost certainly impossible way (with certain diodes failing open and other failing as shorts) to put out AC.
> 
> What is a "capacitance check"?


I agree. I'm not saying don't check the grounds, just that the symptoms that we're listed sound more like a faulty voltage regulator. The diodes you refer to are in the rectifier portion of the alternator, which if you were to look at a general alternator schmatic, they are what turn the AC to DC before the power is sent through the voltage regulator. I could sit here and type out an essay explaining all of this, but for your sake and mine i'll just give you some of the practical experiance I've had. About six months ago my brother called me and told me that every warning light on his instrument cluster came on while driving his '04 GTI home from work the previous day and that when he reved the engine over 1,000 rpm all of the interior lighting turned off. I went by a few days later thinking his voltage regulator had failed, and to my supprise he had just under 13VDC at the battery with the car idleing, long story as short as possible he ended checking it at one point and told me he read 18 Volts, as i rechecked i realized the multimeter was on VAC instead of VDC, as he rev'ed the engine the AC voltage kept climbing while the DC remained steady around 13.4. Granted this is and extream case of an alternator failing and does not happen often, even knowing the theory it doesn't sound likely but it is not almost certainly impossible for it to fail in that way. In more recent history, I had to replace the alternator and battery in my '99 Blazer because the voltage regulator slowly failed, after I replaced them I noticed the dim/flickering interior lights came back to full intensity and the annoying whine coming from my speakers dissapeared...

And yes the measureable output from an alternator depends on the load, but at lower RPMs alternators are not able to output the rated amperage, most stock alternators are are rated to 90 Amps but can not creat that amount of power untill 3500 to 4000 RPM.

A capacitance is typically done on aircraft batteries, but can be checked on any battery to ensure the cells are operating/charging properly and defiantly not something a jiffy lube mechanic can do, I only brought that up because a faulty alternator can kill charging capacity of a battery in a fairly short amount of time.

Please note I’m not trying to be confrontational or condescending with this post, this is just good information that a lot of people don’t know.


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## BassNotes (Mar 16, 2005)

Yes, the symptoms are of a fauty voltage regulator. They're also symptoms of one or more bad (high resistance) electrical connections. It costs a lot less to check and fix electrical connections (and they're more common) than to replace a voltage regulator, so it makes sense to address that possibility before concluding that you need a new voltage regulator. Still, a lot of people will buy the voltage regulator first, discover that they still have fluctuating supply voltages, and often then post on vortex about how perplexed they are even after sinking so much time and money into the problem.

I don't think you mean "capacitance." 

The current output is a function of the load and the alternator's output voltage. Even at high RPMs, the alternator won't put out, say, 90 A if the load isn't there. Usually it isn't; 20-30A is more typical. If the alternator's output voltage drops, so will its output current, but as long as it's 13.5 V or so it's not much to worry about.


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## ttocsybles (Sep 7, 2006)

Again, I agree the grounds are a possibility. But yes I did mean capacitance and simply what i was stating about the alternator is that at lower RPMs the alternator is not capable of creating the higher amperage that it is rated to.


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## BassNotes (Mar 16, 2005)

Measuring capacitance would be appropriate for checking a capacitor, not a battery, so I think you're using the wrong term.

I agree that an alternator typically cannot put out its rated current at low RPMs, but what will happen if it can't deliver what's demanded is that its output voltage will sag.


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## ttocsybles (Sep 7, 2006)

You are correct about the voltage drop if it can't supply the amount of amperage required. Just like the characteristics of a battery, it will drain the available amperage before you see a significant voltage drop. For example, you may be able to read 12 to 12.5 VDC on the battery and think it's still good, where the truth is you actually need to check the stored amperage of the battery with the engine off, as you may still have 12+VDC your battery may only be holding a fraction of the rated cranking amperage, most common car batteries are rated between 400-600 cranking amps. As most multimeters have a max 10Amp rating this is where the capacitance check comes into play. This can also be done with a decent ammeter, but those aren't cheap. if you do a little bit of reading you'll find out that all batteries are essentially capacitors, consisting on an anode a cathode and a form of dielectric. The majority of automotive batteries are 6 cell lead-acid batteries, each cell consisting of two lead plates immersed in an acid electrolyte/water solution working on the theory of capacitance where the voltage is "stored" in the form of the solution between the plates. While charging and discharging the ratio of acid/water changes, but over time many different things can cause the battery to lose the ability to hold a good charge, whether its deterioration of the plates, the solution being too acidic or basic, etc.. 

_Now I know we have strayed from the original topic a bit, but my point remains. As BassNotes stated, check the grounds, it’s a great place to start (cheap and easy to repair). Next, take a look at the alternator. If the alternator needs to be replaced then make sure you have the battery checked, as a failing alternator (or specifically the voltage regulator) can drain the ability of the battery to function correctly._


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## BassNotes (Mar 16, 2005)

Yes, we have strayed off topic, but I have to correct this point: a battery is _not_ a capacitor. There are very fundamental differences between them.

You said yourself that a cap has plates with a dielectric between them, and that is correct, then go on to say, also correctly, that a battery has plates immersed in electrolyte. But what's incorrect is to equate the two very different concepts. Sorry.


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## undwirtanzten (Feb 9, 2011)

man this thread was a good read...and i really mean that. lots of tasty info.

i'm having the same problem, lights flickering at idle and alternator making a whirring sound consistent with the speed of the motor (my father tells me that when an alternator isnt performing properly, it puts strain on the belt, causing said whirring noise).

another symptom i'm having is that vagcom is showing an error in the airbag, tells me voltage too low or unconstant....

my question is, if my alternator isnt performing properly, could it theoretically cause a rough idle and a "p1136 system too lean"?


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## BassNotes (Mar 16, 2005)

I would check all the electrical connections, but especially the grounds on the engine, chassis, and - battery terminal. Bad ground connections cause significant voltage differences among them, and that can cause erroneous sensor signals reporting to the ECU. And it will also cause flickering.

The strain on the belt varies with the load on the alternator and the speed of the engine. The whirring noise could be an impending bearing failure, or maybe defective brushes (pretty rare though), etc.


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## undwirtanzten (Feb 9, 2011)

starting to wonder if a little of that whirring is the fuel pump getting starved of electricity. started car with door open, and noticed the noise seems to be coming from under the car, not under the hood.......revved the engine up to about 1100 rpm, and the whirring changed note and got a little quieter....

is the fuel pump on a vr6 under the car or on top of the gas tank?


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## Non_Affiliated (Feb 12, 2002)

VW Jenno said:


> hey guys,
> 
> i have 05 vw golf, my interior and exterior lights have been dimming or flickering while im idle. when i'm driving the lights seem fine alos when i hit the gas to start driving or rev my car theres a whining noise, i'm thinking they're connected somehow but not really sure. the car hasnt stalled on me at all and hopefully it won't. my mechanic said it could be a faulty voltage regulator. any thoughts on what it could be??? :what:
> 
> thanks Jenn


Maybe It has been asked is the whinning noise only when the stereo is on? Or is it there when the stereo is off? Cause most likely then if there is a whining noise with the stereo off, then it isn't likely to be electrical.


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## Non_Affiliated (Feb 12, 2002)

undwirtanzten said:


> starting to wonder if a little of that whirring is the fuel pump getting starved of electricity. started car with door open, and noticed the noise seems to be coming from under the car, not under the hood.......revved the engine up to about 1100 rpm, and the whirring changed note and got a little quieter....
> 
> is the fuel pump on a vr6 under the car or on top of the gas tank?



The Pump is in tank. If your fuel pump is making noise just turn the car ignition to on. The pump will run for a few seconds. Like in my Corrado it started making noise and before it starts it make s a Wiririrele noise to reprime the system.

also if you want to hear it better, just shooting from the hip as I don't know the 2005 VR6 Golf too well. But there should be the fuel access hatch located in the hatch bay area. Pull the floor carpet and you should see a round cover with three screws holding to the floor. Pop those out and the hatch comes off and you have access to the top of the tank where the pump connects too. You should be able to hear the pump running much better with that cover off and can rule out if that is or isn't the noise.


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## undwirtanzten (Feb 9, 2011)

i'm almost 100% my problem is centered around my alternator, i need a new belt.......that might be my problem even, will replace and hope it does away...if not, i'm getting alternator tested.....


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## BassNotes (Mar 16, 2005)

undwirtanzten said:


> i'm almost 100% my problem is centered around my alternator


Based on what?


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## undwirtanzten (Feb 9, 2011)

BassNotes said:


> Based on what?


condition of belt, flickering lights/whirring noise coming from front end at idle...also have an error code for insufficient or unconstant flow of voltage to air bag, can find no loose connections, grounds all look brand new and are nice and firmly fastened.....also getting a lean code, but have replaced everything from the plugs to the coil, all filters (fuel, air, oil), cleaned throttle body, checked for vaccuum leaks (found one, but fixing it didnt keep the code from coming back), cleaned MAF, only step left in my tune up is to replace the belt yet none of my problems at idle have been fixed......starting to think its either my alternator or my SAI system.


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## undwirtanzten (Feb 9, 2011)

undwirtanzten said:


> condition of belt, flickering lights/whirring noise coming from front end at idle...also have an error code for insufficient or unconstant flow of voltage to air bag, can find no loose connections, grounds all look brand new and are nice and firmly fastened.....also getting a lean code, but have replaced everything from the plugs to the coil, all filters (fuel, air, oil), cleaned throttle body, checked for vaccuum leaks (found one, but fixing it didnt keep the code from coming back), cleaned MAF, only step left in my tune up is to replace the belt yet none of my problems at idle have been fixed......starting to think its either my alternator or my SAI system.


feel free to tell me anything i might be missing, but the above mentioned tasks are all i can think of that might lead to a lean code (other than an o2 sensor). CEL code is p1136 system too lean, then vagcom tells me my airbag is telling me " 1 fault found: 00532 - supply voltage b+ 07-10 - signal too low - intermittent"


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## Non_Affiliated (Feb 12, 2002)

undwirtanzten said:


> feel free to tell me anything i might be missing, but the above mentioned tasks are all i can think of that might lead to a lean code (other than an o2 sensor). CEL code is p1136 system too lean, then vagcom tells me my airbag is telling me " 1 fault found: 00532 - supply voltage b+ 07-10 - signal too low - intermittent"


Not sure on the 120A Bosch alternators if you can just swap out the voltage regulator or if they are internalally regulated. If you have a exposed regulator you can remove, it could be that the Brushes on the regulator have worn down beyond their tolerance, and are bouncing around on the slip rings on the armature. When they wear down the springs lose their downforce pressure and it can lead to them kind of bouncing around on th armature.


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## BassNotes (Mar 16, 2005)

I wouldn't rely on just the eyeball ohmmeter ("they _look_ okay") for checking the grounds and other connections. Take actual voltage measurements across them while the engine is running.


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## GtiPeteypahn (Jan 26, 2011)

only read like the first 10 resonses but did you ever check the belt?


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## undwirtanzten (Feb 9, 2011)

GtiPeteypahn said:


> only read like the first 10 resonses but did you ever check the belt?


this is where i'm at right now. i KNOW i need a new belt....what i DONT know, is can i change the belt myself, or should i pay someone else to do it. cant find a diy for belt replacement and i dont wanna start removing my old belt to find out i cant get it out or cant get the new one in......

how easy is it to change the belt on a mk4 jetta vr6? i looked at the passat diy, and it doesnt apply, belt is on the airbox side on passats and on the passenger side where there is no room in jettas.....


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## VW Jenno (Jan 19, 2011)

i've been bad... i haven't check this thread in a long time! you all are awesome for giving me your 2 cents :laugh:

this is what i've figured so far, not sure if its 100% but its all i got! i took the car in let him drain the battery and that was def dead. so we changed it and my car was beautiful, the lights didnt flicker at all. maybe 2 weeks ago the lights started flickering again! i called my guy and asked him what the deal was, he said if i have an ipod, car charger or anythign plugged into my ac that could draining my car. i had an ipod that i kept plugged in day and night, after i unplugged it the flickering stopped. i'm not sure if that was really the case here but it sure seems like it. i'll let you guys know if it starts get freaky on me again  

PS i think the whinning is a vacum leak :/


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## BassNotes (Mar 16, 2005)

An iPod won't cause flickering (unless its glowing red).


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## VW Jenno (Jan 19, 2011)

you dont think so? i kept it plugged in day and night. when the car wasnt on the adapter would still glow red like it was on. either way, i unplugged it and the car has been fine. hopefully it won't start up again :banghead:


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## VW Jenno (Jan 19, 2011)

soo funny thing happend, i went to the store and the flickering started again :banghead: theres always this whine it makes when the lights flicker and when i heard the whine i turned the lights on and sure enough they were flickering! 

maybe i should just spend the money and take it the dealership


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## BassNotes (Mar 16, 2005)

I mean "glowing red" as in emitting smoke and flames. 

Compared to what else you have going on in the car, an iPod draws extremely low current.


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## BassNotes (Mar 16, 2005)

VW Jenno said:


> soo funny thing happend, i went to the store and the flickering started again :banghead: theres always this whine it makes when the lights flicker and when i heard the whine i turned the lights on and sure enough they were flickering!
> 
> maybe i should just spend the money and take it the dealership


So have you checked your ground connections?


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## VW Jenno (Jan 19, 2011)

i have not checked the ground yet, but i have a feeling thats not going to the problem. i'll check it out and see. :screwy:


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## Unknown Soldier (Jan 6, 2012)

I have the same thing happening to my VR6. I cleaned the contacts on the underside of the battery holder and maybe noticed a slight improvement. Recently it's been slightly cold though and it tends to happen as the engine warms up. So maybe the improvement is only weather related. Very annoying problem. I'll check the voltages next as BassNotes suggested and to clean the ground to the engine. There are three grounds under the battery and one on the engine/tranny to the left of the battery. Am I missing any other main ground points?

I also noticed that my pink coolant was leaking to the rear of the engine from the coolant hose flange (at least that's what I think its called). Didn't know if this could have ruined anything important that is electrical in that area.


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## Non_Affiliated (Feb 12, 2002)

ttocsybles said:


> alternators will put out 12.5-13.5 VDC at any speed while operating, but the amperage is much lower at idle. as the engine RPMs increase, so will the amperage output from the alternator. I guess where I'm going with this the voltage regulator turns the AC power created by the alternator into the DC power that everything in the car run on. a faulty/failing voltage regulator will allow AC current to pass through when DC current is low (at idle). and if you know anything about electrical power/electronics, things designed to run on DC don't like AC.


Whaoh Whaoh Whao..... A properly working alternator with a properly connected electrical systems should output 14V. Most regulators are fixed at 14V.


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## Mister W (Jul 31, 2002)

I have the same problem.
It started 2 years ago. then i cleaned up the 3 ground under battery and another one (probably the tranny) and it stop. Now it started again, and mostly when it's raining or humid.
Sometime when i stop the car or use windows and brake, all dash light blink, beeps, radio turn off, car almost dies for a second then coming back normal.
when i changed my battery, they checked the alternator and it was fine. Belt is old, but doesn't make noise. I'll check those grounds again and that voltage regulator if i can find what it is.
There is a file on the net about where are all the grounds on an MK4, useful.


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## al123 (Oct 21, 2013)

*Similar problem*

Hello I am having the similar problem with My 2000 VW jetta 1.8t. Only when I use my power windows does my exterior and interior lights dim for a split second as I am pressing the buttons. Sometimes when the car is idle and I do this, it almost sounds like the car loses a little power but again only for a second. The battery is brand new. No other known problems with the car, Any suggestions?


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## Non_Affiliated (Feb 12, 2002)

al123 said:


> Hello I am having the similar problem with My 2000 VW jetta 1.8t. Only when I use my power windows does my exterior and interior lights dim for a split second as I am pressing the buttons. Sometimes when the car is idle and I do this, it almost sounds like the car loses a little power but again only for a second. The battery is brand new. No other known problems with the car, Any suggestions?


Besides just cleaning grounds, cleaning positive connections helps too. also Checking regulator brushes helps too. They are a wear part and even if the regulator is good, excessivly worn down brushes leads to arcing on the armature and quicker degridaion of the brushes.


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## Eastpack69 (Oct 9, 2014)

*Lights dimming*

Did you guys ever figure this out, and how you fixed it?
I have the same problem! on top of that I have this loud turbine like sound that happens when I turn the car on, I cant pin point what it is.:banghead:


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## BassNotes (Mar 16, 2005)

Eastpack69 said:


> Did you guys ever figure this out, and how you fixed it?
> I have the same problem! on top of that I have this loud turbine like sound that happens when I turn the car on, I cant pin point what it is.:banghead:


Do you have a voltmeter?

The turbine sound is probably the SAI pump. If it's unusually loud, you might have a loose or broken SAI hose.


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## Ronny Bensys (Apr 17, 2014)

Did anybody ever figure this out? I have similar problem with my 11 SE. All powerful consumers like power windows, A/C, rear defogger cause headlights dim and slight vibration that I feel in the cabin. When I change the shift lever from R to D, headlights dim for a second. My 4 year battery died last year in one week in the parking lot out of nothing. Replaced the battery, was ok for about 2-3 weeks, then the power again went weak. Checked the alternator pulley. It was looking noisy and rusty. Replaced to a new INA pulley. The battery is now charging better than the old pulley but headlights still dim and engine vibrates when a power consumer is started.


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