Strange electrical problems 2003 Accord Euro

Hi all,
I would like to draw on your vast experience and see whether you can help me diagnose an intermittent problem which has started happening with my Euro. I will start with a few details of my car. My car is an 03 model (standard, Auto) with ~ 120,000 km on the clock.
For some weeks I have been noticing some alternator whine coming through the stereo. I initially didn’t think much of it and decided to keep driving till my next scheduled service. More recently however, I have noticed that the headlights were dimming occasionally when the car was slowing down (and especially when the transmission down-shifted), this made me more concerned. Even more recently (last week) the electronics in the car started randomly dropping out e.g the stereo would cut-out and in severe cases the dash indicators (tacho and speedo) would drop to zero. These drops would last a fraction of a second (I have yet to have the engine cut-out).
I have had an auto electrician check the car out. With his computer hooked up, he could register the car voltage dropping to ~ 4V (when the stereo etc cut-out) and then the voltage recovers (in some cases alternator overcharging to ~15V and then settling). The problem is that this seems to happen randomly and is not consistent with a fault with the alternator (the computer is not registering any fault codes). Apparently the auto electrician could not check the alternator out of the car as Honda/Denso use a strange control system etc…

I have subsequently had the alternator swapped for another and this seemed ok to begin with but after a couple of days, this fault seems to have come back! The strange thing is that if I hear the alternator whine, I can just re-start the car and it will be fine!.... The alternator swap-out has at least eliminated one possible cause. If anyone has any ideas I would be grateful!

Ignition relay possibly.I had similar symptoms on a Subaru Liberty 8 years ago and that's what it was.

Have you checked if the ground wire between the negative terminal and the chassis is free of corrosion and is tight?

Thanks for the replies, I have checked the groundin wires and all battery/alternator connections and they are clean and tight. I will explore the possibility of the ignition relay being a cause...
Do you think the computer may play some part given that the problems seem to disappear with a restart of the car? I have heared that the voltage regulation is also controlled by the computer...

This may be a random stab ....
but are you sure your alternator pulley to belt drive contact isn't slipping causing your alternator not to charge your batt.

The belt connects Crank, Alternator and PS pulley.

!!

i think im starting to have the beginnings of the same issue as u lol

headlights sometimes dim for a second, didnt notice if it was the auto transmission down shifting or not - will take notice next time ^^

also noticed my neons tend to dim out for a little bit at the same time my headlights do (i've got interior neons connected using the power for the green ciggie ring light)

only done 65000kms though =/

Hi,
I have checked all the pulleys and they are all tight.
I have done some more net surfing and it looks like some people have reported similar problems with other makes of cars and the culprit has been the ignition switch. The autoelectricial who is looking after me also thinks it may be the multiplex bus as the car also seems to slightly overcharge when recovering from the voltage drops.....extremely frustrating!

i have noticed my lights dimm while on the freeway for a split second, i thought it was my eyes first but its def a voltage issue, my last car would do weird things when the regulator was stuffed.

my car goes through batteries like nothing else!!


oh, i'm talking about my R/C accord though!

*grins awaiting flames*

Well I am still having trouble with my Euro! I recently had the car sitting for a whole day at the local dealer without having any work done because they coundn't find the problem.
I have been driving the car since and the electricals are cutting out more frequently. I have noticed that I can temporarily make the problem go away by stopping, putting the car in neutral and turning the starter motor over for a second...... This makes me think, perhaps it could be a problem with the relay which switches the car from battery to alternator power. Does anyone have any further thoughts on what the problem may be??

random stab, have you tried changing the main fuses??

Hi, thanks for the suggestion, I have checked all the fuses in both the engine bay and drivers side fuse boxes... all of them are intact.

I have experience that when the fuse (80Amps) is broken (hairline crack) cant see it being broken and electricity still flows thru but get distrupted from time to time, thus having weird problems.
You dont need to bother with all the fuses, just need to change the main alternator fuse and test it out, borrow one from your eletrician, return it to him after testing. Dont cost you anything.