Rishi writes:
I am a long, long time lurker but not a poster on TTAC (yet). I have a question regarding a 2004 Honda Accord EX four-cylinder. When I am driving, the headlights flash at different intensities depending on what gear it is in (its an automatic). When I accelerate, and it drops some gears, the headlights flash a bit brighter, but then become dimmer as the car settles into fourth. Could this be a sign of water damage or a major electrical issue? Thanks so much for your time.
Sajeev answers:
Well, Rishi, your alternator is not especially happy at lower engine revs. From what you said, running full throttle when you need functional headlights is the way to go.
Just kidding. Charging problems come from several sources, in no particular order: corroded grounds or battery cables/terminals, a weak battery or a dying alternator. There are several voltage tools you can plug into your cigarette lighter to get real time reading of when (and to what extent) your charging system is failing, or you can go to a parts store and have their staff test the system, complimentary.
Considering your vehicle’s age and that the problem is engine speed dependent, I suspect the alternator. Have it tested, and the battery. If the alternator is burning out the (original) battery too, it might not be a bad idea to replace both at the same time.
Bonus! A Piston Slap Nugget of Wisdom:
If you have an aftermarket stereo (and like to move-it-move-it) with a big honkin’ subwoofer, that’s another problem: adding a capacitor between the battery and the amplifier usually fixes it. And it’ll reduce the parasitic drag of one seriously thirsty subsystem on your car’s charging system.
[Send you technical queries to: mehta@ttac.com]
Rectifier in your alternator is bad.
Maybe also the regulator. If this is the case, you’ll experience fried batteries, ECU and other electrical systems.
Some Denso (I suppose Honda use them) alternators have both in one unit.
You can change it. Easy/cheap fix. Change the brushes while you’re at it.
You can also change the alternator and assure more problem free miles.
Gossip on the Honda message boards indicate that Honda has been using an alternator with minimal capacity. In other words, barely enough output to get by. A bigger alternator consumes more engine power.You are witnessing what is “normal” for a Honda product.
That’s a Euro Honda Accord, known here as the Acura TSX, in the pic. ;)
Start by checking the condition of the battery cables and connections. That’s free, and easy to do.
If nothing obvious shows up, have both the battery and the alternator load-tested. It sounds like one or both are on their way out, and you’re getting a rare opportunity to rectify (pun intended) the situation before the car leaves you stranded.
Another thing to check would be your serpentine belt for looseness due to belt wear or a worn out belt tensioner.
Alternators have three sets of diodes for a total of 6. If just one of the diodes goes bad you get weak charging even though it looks like it’s working. I would try the alternator if it has the internal regulator first. If an external regulator is used, replace just the regulator. It’s possible to test the diodes in an external regulator, not so easy in the built in variety.
Honda alternators are way too undersized, most car audio guys are aware of the problem and use high output aftermarket units. If you’re not running a huge stereo OEM should suffice.
I have an ’07 EX-L with I4/5MT. My headlights flicker slightly when the air conditioner cycles on and off so it does seem to be pretty normal. (My car has done this since new.)
I have issues with the battery draining if the car sits for very long (e.g. when on vacation). It’s annoying in the summer and battery-damaging in the winter. I wonder if the alternator issues mentioned above might be significant in my problem.
If the stock alternator is underpowered as some stated, getting a more amps/powerful one would be better. Staying with a stock/oem alternator could have the problem appear again, the lights could be really dim when heater fan is on high and charging cell phone, etc.
Check out Honda TSB 05-034, “Headlights Dim or DTC P1298 Is Stored in the ECM/PCM”. This happened on our 2003 Accord and the dealer swapped out the ELD (Electronic Load Detector) for free under a goodwill adjustment.
“SYMPTOM
The headlights dim with the engine running and the headlights on, or DTC P1298 [electronic load detector(ELD) circuit high voltage] is stored in the ECM/PCM (but the headlights do not dim).
PROBABLE CAUSE
The ELD has a faulty solder joint.
VEHICLES AFFECTED
2003–04 Accord – ALL”
I’ve never had any reason to suspect that the alternator on our Accord is underpowered. We have a V-6 with every accessory and since the ELD issue was fixed, the headlight intensity is rock solid. Now I don’t have an aftermarket annoy everyone within a ten mile radius sounds system installed …
Both Honda and Toyota are living off their quality reputation earned in the past decade. Switch to a Korean your if you liKe reliability.
Great advice, John. I wonder if there’s a place where we (ME) can look up TSBs from all manufacturers…Alldata used to have it, but I haven’t found that information for free in several years.
One more comment: does any car have an external (not bolted to the alternator somehow) voltage regulator anymore? That seemed to die in the early 1990s. Correct???
Our 1997 Neon has a regulator which is external to the alternator…it’s in the engine control module.
TR4 : Our 1997 Neon has a regulator which is external to the alternator…it’s in the engine control module.
Like whoa. I think you just blew my mind.
Sajeev Mehta
You can find current recalls & tsb info @
http://www.edmunds.com/maintenance/select.html
vegasgti : Much appreciated, it is one of my bookmarks now!
I look up TSBs using the website access for our local county public library. I suspect that many other library systems offer a similar service for patrons. I do have to enter my library card number and a pin code to get access. The same data source also has a very good and comprehensive online repair information library. It is similar to Alldata, but from a different company.
Oh wait, public libraries are part of the massive government run information conspiracy which destroys everything it touches.
Honda TSB 05-034 sounds like the solution. Probably obvious, but do the free and cheap maintenance stuff first. Clean corrosion off the battery terminals and add distilled water to the battery as needed to bring the electrolyte up to the correct level.
The Delphi alternator in my 99 Accord failed at 45k miles. I complained to American Honda and they discounted the replacement cost even though it was out of warranty. The dealer service department said they had seen several failures for the Delphi alternator and none for similar Accords with the Denso alternator.
@Orangutan
That would make it a Euro Accord with a Maryland license plate…
Most Mopars of the mid 80’s through the 90’s used a voltage regulator that was integrated into the power control module under the hood by the battery. It provided the power control and operation of the commands that originated in the logic control module that was inside the car by the passenger footwell. In later models, the two units were combined into one. Don’t really why they were built that way, maybe to save money?
A 2004 car (and a Japanese one, no less) with an alternator problem already? Seriously? My old (1976) Ford truck had the original alternator on it when I sold it a few years back with a mere 188,000 miles on it. Oh wait, that can’t possibly be right since all American cars are junk…or at least that’s what I hear on the internet.