E-man

while i'm driving, my volts (according to my voltmeter connected directly to my batt) will frequently drop down to ~12.4 for no particular reason randomly. it will shoot back to ~14.4 eventually, but only for 10 min at most. i've had my electrical checked out and it registers good in all aspects. also, my battery sucks at holding a charge. drops down quickly if i play my system on moderate volume while my car is off. i have been told it could be my regulator. anybody have a suggestion?

E-man

hmm... nobody? well i've discovered something weird i didn't notice until now as well. when i accel, it jumps down, but when i coast/decel in a gear, it jumps up lol

Sleep_DEPRIVED_Sleeper

may be your car is possesed, call an exorcist!












lol, jk...

May be it's because your car is using the Alternator while it's running and the current draw from the battery is low... i'm just guessing, not an electrical expert...

E-man

haven't figured it out still, but a new development has arrived... when it is down at 12.xV and i use any other electric (window, sunroof, etc.), it jumps back up to 14.xV for like 10sec, and goes back down again... sh!t is weird!

Dan3952

All cars do that, your alternator puts out more juice when it's not idling

E-man

i know that alts put out x amount at x rpm. my car isn't idling when it drops though. it happens whenever it wants to apparently. and yet another discovery i've came across, is that when i'm driving ~50mph+, it stays at 14.xV...

TiggerCarman

I am not expert at all. But I am guessing your alternator is weak, by weak I didn't know is it starting to fail or your alternator output isn't enough for all your electrical system you have in your car. Therefore, under idle or low RPM range, he alternator can barely run the car, and doesn't have enough voltage left for charging. It is recommended to have at least 13.5v even in idle condition. You better check out much power your car is currently using and how much power your alternator is generating at various RPM. This is not something easy to do, you will do it only if you really want to know what is happening. For an easy fix, turn everything else off, or upgrade to stronger alternator and new battery.

p.s. I am not sure why when you use windows or sunroof that will jump up over 14v for short time. But my best guess is because they are some unit with "coil" like electric motor. These unit have a characteristic of "short" as its initial contact, which give your voltmeter a spike, it should not be long at all. It is your voltmeter take a long time to average out this spike.

Poisonsnak

E-Man you're not alone - I have the same issue.

In situations with low electrical load and low RPM the alternator seems to shut off as my system voltage drops to around 12.7V. Increasing RPMs or increasing electrical load will cause the alternator to turn back on and system voltage is around 14.3V.

With a very small electrical load (only DRL headlights) I need to be at around 4000 RPM for the alternator to be on, with a slightly higher load (add stereo) the min RPM drops to around 3000, and with a heavy load (heater fan and defog wires) the alternator seems to be on continuously.

The reason I say the alternator shuts off is because with a tiny load on it the voltage is rock solid at 12.7V, repeated revving of the engine (staying below 3500 or so though) doesn't budge the voltage at all.

My situation is even a little weirder as my alternator is only about 2 weeks old (just replaced it because I plan to do stereo competition - maybe)

Currently I think the behaviour is either by design or there's a problem between the ELD unit (electrical load detector - by under-hood fusebox), the ECM (fuel computer), and the alternator voltage regulator (brand new in my case). From reading my service manuals the systems seem to inter-operate as follows:

ELD measures electrical load and provides some kind of output signal
Signal from ELD is fed to ECM
2 signals from ECM go to Alt VR (or maybe 1 signal each way?)
Alt VR controls Alt field current (basically controls output voltage of Alt)

So my guess is the ELD tells the ECM how much load there is and the ECM decides based on this and the engine RPM whether or not it wants the alternator operating or just spinning freely.

I think I might stop by the stealership and ask how much a new ELD unit is, if it's only 20 bucks I might give it a shot and report back.

E-man

hmm... yeah let me know how it turns out. i'm a bit of a stereo enthusiast myself so i was going to up my alt, as well as my batt. still have to do the big 3 too...

Poisonsnak

Well just went by the dealership I guess the whole fusebox needs to replaced and it's over 200 bucks canadian so I think I'll maybe just try to troubleshoot it some other way.

Poisonsnak

Oh hey I just found this by some quick googling:

"1997-1999 Acura CL/1998-1999 Honda Accord

July, 2001




1997-1999 Acura CL
1998-1999 Honda Accord
Lester # 8220

This alternator is designed with the ELD charging system. This system allows for better fuel economy and adjusts idle speeds during periods of heavy electrical demand. In some cases the C terminal will turn the alternator off through the computer. If you are not sure if the unit is bad or the computer may be at fault, cut the "C" wire and the alternator should start to charge if it is good. Of course when cutting the wire leave enough wire so it can be reconnected."

source: http://www.genco1.com/tech_tip_details.?id=64

So I would say the behaviour is by design but I will cut the C terminal (one of the 4 wires on that green connector, can't remember which one) to see if the alt stays on all the time.

Poisonsnak

Sorry to be such a post-whore but I found this really great writeup of how the alternator works on the CL and accord:

http://findarticles.com/p/articles/m...07/ai_n8866330

They say that the ECM grounds the "C" terminal (white/green wire) when it wants to turn the alternator off but it's not off, it's in "low charge mode"

213swampy

iTrader: (1)

Hey did you guys ever find out what the problem was I just notice my car is doing the exact same thing?

antonio3rd

its an ELD sensor put on hondas to save gas. cuts out while driving at certian times

mossman77

So is there a safe/effective way to bypass this functionality? It's causing my subwoofer output to vary, which is irritating. Maybe I should install my own regulator on my amplifier so it never varies. If defeating the ELD sensor is possible, I'd rather go that route.

ChaddyOwl

I know this is an old topic, but I stumbled across it while trying to diagnose an alternator problem on my 2006 RL, and found it interesting.
In searching the web, I came across this nice paper titled "Honda's Dual-Mode Charging System" from Southern Illinois University, which has great descriptions of the functions and various signals involved.
https://opensiuc.lib.siu.edu/cgi/vie...text=auto_pres

R.L.B. Aging

That was an informative post on the Acura dual-mode charging system. Same issue here, battery replaced twice and alternator replaced when it's probably a faulty Electric Load Detector (ELD) that's caused the check charging system light and sound to flash and ping on constantly the past few years when running the car at low loads, with the radio, heater/AC, lights, etc. all off. It's not seen that ELDs are available as parts for for the 2005-2008 RLs anymore though, but they they are seen as cheap parts for other later acura models. It's assumed RLs have one, as low charging system loads constantly have the check charging light and bell ringing, so much so, that the radio and AC/heater are always left on, depending on what season ,to keep the load up in the high 13s-14 volt range to stop the dash battery warning flashing and noise. . One workaround seen on youtube, was inserting a ~ 50 cent 820 ohm resistor between two of the ELD wires. I'll be off to the dealer or an auto electrician in the next couple weeks to see if they are aware of the 2005-2008 RL ELD low load check charging system warning phenomena and if they can fix it.

R.L.B. Aging

An update on a faulty ELD from the Acura dealer, they say on RL's it cant be separately replaced. The fuse box has to be replaced in full, to the tune of $950 in 2022. So, that's not really an option, as much as this vehicle is liked, and as annoying as the erratic and intermittent low-alternator-load ring-a-ding ding of the check charging system dash warning light is. As previously mentioned, under low charging system voltage loads and low car revs and speeds, the check charging system light sometimes but not always, likes to flash on and off with a bell ring a ding ding to tell you sonically. WIll seek out other options to fix this. This ruckus is directly related to randomly fluctuating voltage drops into the 12 volt ranges as measured by a voltage gauge. So will pursue another option.

R.L.B. Aging

Ok, regular Hondas are affected by ELD issues as are Acuras. A few youtube videos show owners who've changed batteries and alternators unnecessarily more than once to try to remedy the check charging system issues and in some examples 1298 error codes. The two examples below are for a Honda accord, where a full fuse box replacement is advised by dealers. In the link examples an accord fuse box is taken apart, the ELD identified, and replaced by an ELD from a CRV.

R.L.B. Aging

So, a salvage yard fuse box from a lower mileage Gen 2 RL was retrieved and installed today, and took about an hour. The RL was road tested for half an hour under a low load, no radio, AC, lights etc. and did not throw any check charging system warnings or the accompanying bell ringing.

The 12 V butt lighter receptacle voltage gauge shows the ELD keeping the voltage in a narrower range the the previous older one, the charging voltages appeared to bottom out at about 12.4 V, and not venture down into the 11 and 10 V ranges like the previous fuse box ELD did. Perhaps this tighter range is normal, and why no check charging warnings happened, it's hoped..

The Honda dual mode charging system does constantly manipulate the alternator output voltage, and the voltage gauge reflects this, with the alternator output voltages dropping down to the lowest volts at the lowest electrical loads coincident with the vehicles lowest engine rpm and speed, often at stoplights when idling. It appears if the out voltages don't drop below 12.4 V as mentioned, the check charging errors have not occured after this one test drive. More info will be reported in a few days after some more low voltage load driving is completed. As mentioned, the check charging errors happened at lower loads, which is not intuitive if one has a regular charging system, not Honda-Acuras dual mode charging system that tries to save energy.

R.L.B. Aging

An update on the check charging light and bell issue after replacing the 16 year old fusebox with a 14 year old one, and some more driving. The annoying Acura RL check charging system light and bell have returned, intermittently under low load conditions. The charging voltage has dropped below 12.4 V during this drive when idling at stop lights, but seems to stay above 12 V, Regardless, the "new-old" fusebox has not worked to rid the RL of it's check charging system problem. The alternator positive lead grounded to the alternator metal cover, hasn't shown low voltage, is always above 14 V, and there is little to no voltage drop from the battery positive lead out to the alternator positive lead in, on that wire/cable. So, the issue appears to be,under low loads and lower revs generally, the ELD and ECU interplay, on their voltage control instruction to the alternator to lower its output V, being fed back to the new battery. It's possible the new-old fusebox ELD has the same issue as the older removed one, the 2nd old ELD is faulty too. The 2001-2009 decade Honda-Acuras seen online often appear to have the ELD check charging issues. It's not certain at this point of the troubleshooting, what, if any, a faulty internal voltage regulator in the alternator might have, in the ELD-ECU feedback loop sent back to the battery under low loads. It's a catch-22 at this stage, if it's a faulty ELD sending incorrect signals to the ECU, a working ECU might then send too low voltages to the battery, that the ECU then also flags, as being incorrect to the vehicle driver. It's possible too, the ELD is working OK, outputting correct signals to the ECU, but that part of the ECU used to monitor and output charging instructions is faulty. Other possibilities, a harness wire or connector problem, but the check charging system light is random, not correlated with driving on bumpy roads etc. where a bad wire or connector might be expected to act up. The vehicle electrical system ground screws have been cleaned, the 3-4 that were found. The troubleshooting continues...

R.L.B. Aging

Some further notes on the persistent 2006 Acura RL check charging system errors-

As mentioned in the 5th note after the new-old fusebox from a 2008 RL was installed, with a different ELD, the Check charging system error returned at low speeds (stoplights and stop signs) low revs, (at idle or just above) and low voltages (12.3-12.5 v), when the Honda dual-mode charging system goes into energy saving mode producing those low voltages based on the ELD-ECM-ALternator dance that the 3 electrical components do.

The dealer was asked if the previous vehicle owner installed a Denso OEM or third party alternator a couple three years ago, and verified it was non-OEM. So, rather than change a newish alternator, the fusebox was opened and the ELD was unplugged without any resistive jumper attached between the orange-gray dashed 5V ELD feed and the black center ground wire. It was just unplugged in the bottom fuse box area, and left electrical taped to an adjacent plug's lead wires, isolating the ELD.

AFter the above, the vehicle was driven a few tens of miles and did not drop below 13.9 charging volts as read on a 12V plug-in volt meter. The average charge voltage was somewhere in the 14.3-14.5 range, under all electrical loads, with and without the headlights, AC, stereo, and navigation on or off. There were zero check charging system warnings with a red flashing battery nd accompanying ting ding ding ding distracting noise.

So, either the non-OEM alternator is not in sync with the Honda ELD and/or two ELDs, one 16 and one 14 y.o. are causing the check charging system light and bell to activate at low battery loads, and low car speeds & Revs, when the battery and alternator should just be chilling and saving energy & wear & tear, according to the ELD and ECM observations and commands sent to the alternator. and battery.

It's not known yet if disconnecting the ELD has any side effects, none were apparent during the one hour drive on highways and city streets.

When time allows, a reman Denso alternator will be purchased, the ELD plugged bag in, so to check if the non-OEM alternator was the check charging system trigger. RIght now, it appears two teenaged-old ELDs may have been the check charging system error trigger.

R.L.B. Aging

OK, been driving round now for a few months with the ELD unplugged. The car runs fine, with no annoying low voltage or charging system bells whistling and dash lights flashing. The charge voltage stays pegged at 13.5 volts and above generally with the AC and radio usually on. No adverse battery charge effects are seen, the charge stays up near 12.8 V without any issues so far. Car starts easily when below zero.

The one thing noticed, if you scan the vehicle with one of the fault scanning tools, it will flag the unplugged ELD. I've just ignored this. A possible remedy to this, would be to insert the two leads of a resistor into the unplugged ELD plug, avoiding the 12V connector. Another is to remove the exterior fuse box, tear it apart, and look for a cheaper, say Honda CRV ELD, that might fit in the RL fuse box. As the ELD error only shows up when scanned, this was not done here. Just unplugging the ELD works, and the RL does not light up like a noisy christmas tree when driving around town in slow alternator speed low voltage conditions anymore