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Discussion Starter · #1 ·
wierd problem...

Just bought a new (for me) wagon tonight with 209k. Driving in the dark for the first time I notice the headlights and dashlights (entire electircal system) flutters above 1800 rpm or so. Even when parked with car in nuetral (so it isn't a loose wire on road bumps) up through 1500 rpm no problem...then suddenly flickers??? Not like blinking but quickly flucutates from bright to dim quickly like almost with the rpms of the engine.

The guy a bought it from said it has a new alternator..(doesn't look brand new, but does look newer than the rest of the engine) I assume new alternator was installed to try and fix the flickering lights but it didn't.

Any other ideas? I assume voltage regulator is internal to the alternator? Any other ideas?
 

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That sounds like a bad alternator to me. Maybe the guy bought the "new" alternator at the junkyard, thats what the previous owner of my car did. If you have a voltage meter hook it up to the battery terminals while the car is running. If your alternator is working properly you should get a voltage reading of about 14 volts.
 

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Discussion Starter · #3 ·
So isn't there a separate voltage regulator? The alternator puts out 14V to the battery, but the rest of the car doesn't run on 14V does it? Isn't there a regulator that keeps the main wiring for the car at 12V if that was failing would that cuase flutter?

Or does the alternator output directly power the rest of the car?
 

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Have to say your"new"alternator isn't up to snuff. Possibly as 98escortkid said as it was a pre-owned one or just a cheap bottom of the barrel one that didn't last. Even new parts are defective at times.
 

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Discussion Starter · #5 ·
Sounds like two votes for the alternator...but can anyone confirm whether of not the voltage regulator is built into the alternator or not?
 

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Discussion Starter · #7 ·
Got it! Thanks Ghost.

So I just did the laternator "test" in the haynes manual. I'm getting a steady 14.7 Volts across the batter at 1500 rpm with everything off and a stready 14.5 at 2000 rpms with everything on (A/C high-beams etc)

So alternator seems to be doing good things? So I'll have to check the voltage regulator maybe? Or would that show up across the battery too?

I always thought the voltage regulator only regulated the voltage to the rest of the car, but didn't regulate voltage sent to battery. Is this true?

So the alternator could test out properly at the battery, but maybe my voltage fluctuates in the rest of the system becuase of the regulator?

Otherwise maybe something to do with the headlight switch?
 

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Any voltage that gets sent to the battery gets sent to the rest of the electrical system and the battery output of the alternator has to be regulated. If it wasn't then the battery would fry. The whole car runs on 14 volts just fine, if you start getting above 15V then I would start to worry. Your voltage meter probably isn't telling the whole story. Digital ones don't react to changes in voltage instantly so you can have something fluctuating and the meter might not show it.
 

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if you start the car and remove the negative battery cable, does it stay running? if it does, the alternator is working.
 

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Discussion Starter · #10 ·
pextor said:
if you start the car and remove the negative battery cable, does it stay running? if it does, the alternator is working.
I was told to never do that...that you were almost gauranteed to blow your alternator becuase the battery buffers the alternator from load spikes. :eek:

But maybe that is just with GM vehicles :lol:
 

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it's fine to do it on your escort. I can't say for GM's - no junk in my driveway lol
 

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It's defnitely the voltage regulator on the alternator. When I replaced mine last year with a NAPA brand, I had to go thru 3 of them before I found one that didn't exhibit this fluttering behavior. And now, the fluttering is back, but I've learned to live with it. Since the alternator came with a lifetime warranty, I'll get around to replacing it someday.
 

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Discussion Starter · #13 ·
rbailin said:
It's defnitely the voltage regulator on the alternator. When I replaced mine last year with a NAPA brand, I had to go thru 3 of them before I found one that didn't exhibit this fluttering behavior. And now, the fluttering is back, but I've learned to live with it. Since the alternator came with a lifetime warranty, I'll get around to replacing it someday.
So do you still think it is the voltage regulator? If so, why are you going to replace the alternator? Do you think maybe your alternator is making the voltage regulator go bad??

thanks for the input, glad to hear from someone having the same issue!
 

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I'm eventually replacing the alternator because it has a lifetime warranty. The voltage regulator by itself is $40-70. It's doubtful that the alternator is directly causing the regulator to fail. I suspect that, like any electronic component, some will fail from heat stress after a while.

According to my mechanic, alternators & starters are the worst when it comes to remanufactured auto parts. I just think that the rebuilders are using cheapo voltage regulators with a relatively high failure rate. And the fluttering is not considered a failure (it tests OK on any alternator tester).
 

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Discussion Starter · #15 ·
got it, sounds like a reasonable hypothesis. I wonder if buying a voltage regulator from the stealorship would be high enough quality?
 

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rbailin said:
I'm eventually replacing the alternator because it has a lifetime warranty. The voltage regulator by itself is $40-70.
:eek:

I also have a lifetime warranty alternator(cost $95) and have had it replaced once. It came with a new voltage regulator each time. Might be something to look at. :)
 

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The voltage regulator is Motorcraft P/N GR822, same as what you'd get from the dealer, but you might find it cheaper elsewhere. It's OEM quality, so that's not an issue. But since it's an electrical part, it's not returnable no matter where you buy it.

Note that you'll probably need a Torx T-15 to remove the 4 machine screws holding it in after removing the alternator from the car.
 

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Discussion Starter · #18 ·
conclusion

With day light savings I'm driving in the dark almost all the time now, so last night I finally got off my butt and installed the alternator off my parts car and it fixed the problem.

I knew my parts car (before it dropped a valve seat) didn't have the flickering lights problem, so if the flickering was from the alternator, this should've fixed it, and it did.

The problem alternator did look "newer" than the one I put in there, but it must've just been cheaply rebuilt. Maybe a voltage regulator would've fixed it?? Who knows.
 

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Have the exact same problem on my 99. The alternator was just replaced about a year ago with a 'quality' unit, fortunately it has a lifetime warranty. I'll be swapping it out shortly. It sounds like a voltage regulator problem and without a scope, I doubt you would see the fluctuation on a meter, digital or analog.

Sounds like a case of poor quality due to almost everything being built overseas these days.
 
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