98 CRV voltage fluctuations.

I bought my 98 CRV used a few years ago. It has always had voltage fluctuations. This is noticeable at night with the headlights. The headlights and dashlights both snap bright and then snap back to dim
randomly. I prefer to drive with my lights at full brightness. I seem to have no problem with my battery maintaining a charge. It is just irritating to not have decent headlights at night. Anyone seen this problem before?
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This is normally a bad Electrical Load Detector.
Some ELD's are part of the fuse box, and some plug into the fuse box and are replaceable. I think yours is the first type, in which case the cure would be to replace the under-hood fuse box. If you have the second type, you'd replace the ELD the way you'd replace a relay.
Is your Check Engine light on? A bad ELD is supposed to set an error code, but does not always do so.
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Tegger

The Unofficial Honda/Acura FAQ
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Michael wrote:

Hi, Is your radio noisy particularly on AM band. Then it could be alternator/regulator problem.
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I have a 98 CRV and it developed this same problem. In my case it turned out to be a faulty alternator. I would have your alternator load tested by someone who has the right equipment to see if the output fluxuates under load. In this case I would not bring it to an autozone type place because the equipment that they have in my area will not necessarly pick this kind of problem up. If everything checks out OK I would go with Teggers solution.
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maumee wrote:

Thank you all for these suggestions. I will look into these solutions. I do not have any am radio noise.
sometimes the voltage is affected by engine rpm. Often when I slow down, the lights get brighter. This is not always the case but it happens often enough to probably mean something to someone with the right knowledge. I realize this is counter-intuitive. You would think that higher rpm would generate more voltage. But, as I said, there is no gradual effect. It just snaps bright and then snaps dim.
I have a manual for this vehicle. I will look at the diagram to see what kind of stuff is in the under the hood fuse box. I don't know what an ELD is but I might find it with a google search.
It would be great if this ELD whatever it is could be replaced easily. I do have a local repair man named Tom who has taken care of my car and I trust to be honest. I have never mentioned this problem to him because it is intermittent and sounds like it would be difficult to solve if the problem did not show up in the shop.
Thanks again all for volunteering your knowledge.
Michael
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Michael wrote:

it is, but i have recent experience with something that may be relevant here and stop you chasing that wild goose. eld's are solid state, and the probability of malfunction is ultra small.
my civic, when cold, and coasting down a gentle slope, would speed up and slow down of its own accord, repeatedly. all the typical reasons for this symptom were eliminated. then i changed the alternators and for a while the problem went away for a while. then it started to creep back, and i suspected the eld, electronic load detector, since this was clearly something to do with the charging circuit and the alternator had scratched the itch. i changed the eld, and zero difference. everything else eliminated, but certain of diagnosis, i changed what was otherwise thought to be a good battery since it was the only other possible link in that chain - problem completely gone.
conclusion, the eld was detecting current draw outside typical ranges from an old battery not accepting a charge very well, and the ecu was causing the electronic idle controls to over-compensate and thus affecting engine behavior. in your case, if the ecu is updated to prevent this potentially dangerous behavior on engine speed, the charge voltage would be fluctuating considerably instead, and that will show as light brightness changes.
i therefore suggest that given the age of your vehicle, [you don't state the mileage], you replace the battery, and consider replacing the alternator, even if it tests ok. alternators generally give up the ghost in the 100-150k range, so you're probably in that zone regardless of how it tests at the moment.

with respect, that makes no sense. would you go to a doctor for eczema and not tell them about also having blood in your urine? print this thread if you want to be sure of communicating, but tell him so he can fix the problem for you!

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Thanks Jim, Batteries are pretty cheap at Walmart. I will replace it. Even if it does not solve the problem, I does not hurt to have a new battery in my car in the middle of an upper peninsula winter. I already went to parts houses looking for the ELD. They never heard of it. My Honda manual does not have part numbers. I did a 30 minute search on Google for this part without any success. I looked at it inside my fuse box this morning and it looked to be easily replaced. I would replace it anyway if it did not cost a lot of money.
I see from my manual that my alternator has a self contained voltage regulator. So, replacing the generator really eliminates a couple of possible sources of this problem.
I like the battery idea. My car gets exposed to -40 sometimes. This tends to shorten battery life. I have no idea why but from talking to others they also find this to be true.
I have a couple of extra headlights installed with a relay to my battery. I get the dimming whether I am on high beam with these extra lights or on low beam, with a normal load.
My Honda has 100K on it.
On another note I had a serious charger problem on a ford minivan a couple of years ago. All electrical power to the car suddenly failed. After some serious investigation I found that the battery had shorted and then burned out the alternator. Thank God it did not burn up any wiring.
Michael
jim beam wrote:

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Michael wrote:

it's only a honda oem part. tegger's website has listings of online parts retailers. but don't bother replacing it - it won't be the problem.

this is a significant factor you should have mentioned before - depending on the installation, this can be the entire cause of the problem.

ok, you live in a cold location, with the electric heaters on, extra lights on, the fan on full blast... the electrical system is maxed out. and the alternator will almost certainly be approaching the end of its life. even so, you need to minimize load and this will minimize voltage fluctuations. turn stuff off once you're warm, the car is defrosted, etc. - don't just leave it on.
for lighting, examine whether you really need it. you're better off getting some of the newer oem pattern tungsten bulbs with a higher color temperature than monkeying with extra lights and cutting into the oem wiring.

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If you have a multimeter and a battery hygrosope (both cheaply available) it should be easy to determne if the battery is failing to accept full charge.

The Electrical Load Detector is a dealer item only. And not all cars have them.

Because they change from time to time, so there's no point.

That's backwards. HEAT shortens battery life, not cold.

Oh, so you have aftermarket intrustions into the faxtory wiring, and aftermarket loads on the electrical system. I should have asked first. Have you tried disconnecting the extra lamps to see if the problem goes away?
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Tegger wrote:

I do have these items. Like I said, I do not have a problem starting my car, or having the battery go dead. I will turn on my battery heater and then check the voltage today.

Well, maybe extremes of both heat and cold shorten battery life. I lived in North Dakota for a few years and if your car was left in an unheated garage, the battery would have a short life span. We have block and battery heaters in our cars, but we do not use them all the time because of the expense. So, the battery just gets heated up when we want to drive the car.
I forgot a battery in my tractor last winter. It sat in the cold all winter. It could not be charged again. I had to replace it. That same battery went through a winter just fine when I had the tractor in a heated barn.

My extra headlights are not connected to the system unless I click on my high beams. So, there is no extra load on my electrical system when I am switched to low beam. This problem occurs in both high and low beam. The extra headlights are connected through a relay directly to the battery. There is no path of wiring that might be damaged by carrying too great a load. So, again, when my headlights are dimmed these extra lights are disconnected.
Michael

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Tegger wrote:

Hi, Really so. I lived in Phoenix and now here in Calgary Alberta. Seen more battery trouble down there than up here. One failing cell in a battery can show that kind of problem too.

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maumee wrote:

Hi, Oscilloscope will pick up that kind of problem visually. Ordinary volt meter is not fast and sesitive nough to catch the problem.
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