lights dim or intensify according to rpm's

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sbaker0421

Junior Member
For the past couple of months my interior and exterior lights have been intensifying or dimming according to the rpms. All lights stay at the their brightness while I'm driving. They dim when the idle drops down past 1000-1200 rpm. Have replaced spak plugs/wires/distrib cap/ and rotor. I also put new battery in it and didin't change anything. Can someone help me? Thanks
 
Also check your battery terminals.
 
could be your alternator but i wouldnt worry to bad about it yet....its prolly just that your alt isnt spinning fast enough to get alot of power going at that low rpm engine speed....does that to me too...
 
Mine does that...when I turn my headlights on I can hear my engine slow a little, then I turn on the heater, slows a little more...the engine is just working harder with the more things that you turn on...when I come up to speed my engine powers everything up to full capacity and away I go...

Jason
 
basicly there all good ideas if you are going to try to solve the problem, try all the methods that dont envolve you buying anything then wrok your way up, basicly trouble shoot with the all the different ideas just thrown at you and start with the most easy and cheapest things first.;
 
It's definately an alternator problem. If the belt is tight start shopping for a new one.

FYI any parts store will load test it and you will know for sure.
 
Originally posted by solblu@Jan 13 2004, 12:25 AM
It's definately an alternator problem. If the belt is tight start shopping for a new one.

FYI any parts store will load test it and you will know for sure.
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I disagree. Let's look at how an automotive electrical system works...

Basically, the alternator serves as the primary electrical source, with the battery taking up the extra load when it needs to. The battery's main purpose is to start the car, and on occasion (idle with every electrical device on), help the alternator supply power.

Now, if the lights dim at low RPM, but are bright above 1500 RPM or so, the alternator is most definetly doing it's job, and it's the battery that is not. Load test the battery and I'm willing to bet my car that you have a bad battery.
 
Originally posted by B16+Jan 14 2004, 01:05 PM-->
B16 @ Jan 14 2004 said:
Originally posted by Loco Honkey@Jan 14 2004, 09:49 AM
Load test the battery and I'm willing to bet my car that you have a bad battery.
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sbaker0421
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B16 @ Jan 14 2004 said:

I also put new battery in it and didin't change anything.
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hah...

Loco Honkey's reading comprehension skills = Unsatisfactory.

*puts on dunce cap and sits in the corner*
 
Also if you have a bumpin stereo, but no capacitors, It will sometimes do this. My friend's civic had that problem. It also dimmed the lights when ever a hardhitting song was playing. The lights would dim to the beat of the music.
 
If you have a friend with a volt meter, chech the batt voltage with the car at idle. if it isn't in the high 13's. The voltage regulator is giving up the ghost. Also, while a load test is in order... You can test the static charge of the alt at idle with the same volt meter. if it is low you know your problem.. As a prelim, I often go for a real world load test- using the car. While checking amps, kick on the radio, brights, rear window defroster and A/C and see if you plummet. Those terminal ends are important too. Good luck.
 
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