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Discussion Starter #1
recently purchased a base RSX and when driving it at night for the first time I noticed that all the exterior lights pulse very subtly. Not a huge amount but if you're next to the garage door with your headlights on you can see a slight pulse in intensity. Stops when only under battery power. Had the Alternator checked and its good. Any suggestions or ideas. I walked around the car and the brake lights are slightly pulsing too. All lights, to include the dash lights make a minor pulse.
Also have weird static sound coming from the radio (Pioneer) that seems to come from the left front speaker. Not sure if related?
Help ?
 

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I would still bet it is the alterator. It sounds like a rectifier has gone south on you. Especially since it only happens when the car is running. Battery power, steady lights. Disconnect the negative terminal of the battery while the car is running. The car should continue to run powered by the alternator. Check lights when you are doing it. Get back to us with the results.
Paul
 

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Its generally recommended to not disconnect the battery on a running vehicle because you could induce a voltage spike. Dont know how true it is but it makes sense and I wouldnt try it to find out.

The pulsing is probably due to the electric load detector (ELD). The ELD basically controls the alternator output to compensate for electrical loads. At idle with a steady load you will see the lights "pulse". Normal behavior, but make sure your battery connections are clean and tight as well as any chassis grounds.
 

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Discussion Starter #4
Perfectionist- I did check and clean the negative battery connection. It wasn't bad but I did it anyway. No difference same results. Still a small pulse occurs.

Raven01750-I will check on the disconnecting of the battery and see what that does.
 

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You sure you want to do that? From troubleshooters.com ...

Your battery does more than just provide electricity. It also shorts AC spikes and transients to ground. Removing the battery from the circuit allows those spikes and transients to travel around, endangering every semiconductor circuit in your car. The ECU, the speed sensitive steering, the memory seat adjustments, the cruise control, and even the car's stereo.

Even if your computers and stereo remain intact, in a great many cases removing the battery burns out the diodes in the alternator, necessitating a new alternator. If disconnecting the battery interferes with the voltage regulator's control voltage input, it's possible for the alternator voltage to go way over the top frying everything.

Even the initial premise was wrong. If you disconnect the battery and the car conks out, you don't know if it conked out due to insufficient alternator current, or whether the resulting transients caused your ECU (the car's computer, which controls fuel mixture, timing, and much more) to spit out bad data, shutting down the car.

Nobody should EVER run your engine without a battery.

And yet when you tell them not to, they'll roll their eyes. "I'm a professional. I do this every day. It's fine!" They'll sound so authoritative. So commanding. So in charge. So intimidating. But they're wrong.

The problem, of course, is that disconnecting the battery doesn't always damage something. It does it only sometimes. Less experienced jump start professionals and automotive technicians figure if they got away with it a few times, it must be OK.
 

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Discussion Starter #6
Perfectionist-Ok, I'm convinced. Especially when the specific component inside the alternator that would be causing this pulsing is the rectifier which would be the same item that if the battery were disconnected would have to regulate the ALT output voltage minus the battery connection. Another words by disconnecting if a spike occurred it would happen due to the voltage regulator/rectifier being bad, which is what I/we suspect is bad anyway...or at least I think its about to completely go out and stop working. Anyway, I have ordered up a new alternator and will replace it once it arrives. Will see if it fixes the problem.
 

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I have a similar issue which resolves itself when my headlights are turned on. I’m thinking it’s the EDL or whatever it’s called, I might try to disable it with kpro when my car gets fixed by the body shop - somebody smashed into my car in the parking lot :/


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No it was like that when I got the car, haven’t had the chance to figure out what it is yet. Now the car is just sitting waiting for the idiots insurance company to come look at it.


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OK. Heres another idea that cost nothing. Start pulling fuses and see if a sub-sytem is causing the problem. That is if the new alternator doesn't fix the problem. Just another thought.
Paul
 

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I had a similar problem which seemed to resolve simply.

Pulsing headlights, plus dashboard warning lights for air bag, battery & check engine.

This happened within 2 minutes of starting and lasted for 15 minutes each time. It would happen for several days in a row, then clear up. I noticed it always occurred beginning the day after a long, heavy rain.

I opened the hood early on a sunny, windy day, and left it open for the daylight hours. The problem never occured again.

Hope this helps. If so, it sure is cheap.

-Jim
 

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Discussion Starter #12
OK, I was slow to post the final results but wanted to follow up to those who are tracking this issue. I did replace the alternator and it did resolve the problem. What is weird to me is that I had the old "bad" alternator checked both in the car and at the bench test offered by O'Reilly's and it passed both with flying colors. It shows that it specifically checks the rectifiers and it was good. My only ideas on that is that if there are 5 rectifiers and only one is bad its not enough to cause it fail the check since the other ones are still working. But the one bad one is what is allowing a small amount of "Back-flow" (my word) that would cause the mild pulse of all the lights (interior and exterior).
The other stuff to post for others is that for me I had to do more than what the DIY post states. My guess is that this is due to the extra room I needed to get my hands in that area. I had to not only remove the ft bumper and the headlight but also had to loosen the radiator and condenser as well as completely remove the radiator overflow catch container. I also had to replace the electrical connector on the alternator because the lock tab quit working that locks it in place. The wires on both the voltage regulator (the one I replaced) and the battery wire were ridiculously short. I found out why when I replaced the connector with the new pigtail that added some extra wire length. The extra length causes interference when you re-attach the new pigtail. Right at the point where the butt connectors now were. Overall, this was a super labor intensive job. Yes, I have the confidence that I did it and not some punk kid in a hurry...but it took way too long. The good news is that I could now do it a lot faster now if I ever had to repeat the repair. Never worked on a car that has such close quarters in the engine bay.
 

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Glad to hear it. And the problem not being identified through normal testing doesn't really surprise me either. Without an O Scope to actually see the voltage being generated, its very difficult to see the failure. Happy New Year.
 
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