Honda Accord 2004 lights dimming

I have a honda accord 2004 and when the air conditioner is on the lights
dim for a brief sec.about every 12 to 15 sec.when the fan starts up it
even does this when the motor is cold . I have taken this to the dealer
and they say it is a normal thing for this car. Does anyone else have this
problem?

 

I just noticed this last night as well. I have never experienced this
before, and I have done a good bit of night driving. I even turn off the
system and it still does it. It's not a regular occurrence either. Do you
have foglights on yours?

Must be a voodoo thing going on....

 

You aren't alone. I've experienced this with my 2004 Accord as well. The
dealer told me the same story, that is was normal, but didn't say why it
was. I haven't noticed this in a while but then again I don't do as much
night driving as I did a couple months ago. I can't remember if the a/c had
to be on or if it did it regardless. Oh, and no, I do not have fog lights.

Richard

 

This would be consistent with an extra electrical drain on the system,
much like when you turn on a room A/C, lights on the same circuit dim.
With a car, there is the added factor of the extra mechanical drain
caused by the A/C compressor kicking in that slows the engine slightly,
thereby reducing output from the alternator. If you listen to the engine
carefully, you can actually hear it.

Electric motors have a very heavy initial drain when they first start
up, which is why circuits with large motors on them require delay fuses
to prevent them from blowing prematurely.

 

Yes i do have the fog lights on my accord too but it even does it when they
are off

 

sounds normal.

 

My '03 Accord does the same thing; I got the same line as you from my
dealer.

It's highly annoying. Maybe I'll look into adding some of those 1 Farad
capacitors normally used for car amplifiers to the headlights...


--Gene

 

Here's the answer from Honda, not sure why the dealer won't provide this to
you...

Headlights & Dash Lights Dim With Electrical Load
NOTE: This article applies to all Honda models
except Passport.
Soon after the change from daylight savings time to
standard time (the last Sunday in October), Tech Line
gets numerous calls about flickering or dimming
headlights and/or dash lights when the brakes or turn
signals are used.
This flickering or dimming happens when the battery
is supplying most of the current for the electrical load
instead of the alternator (something a customer is
more likely to notice when their headlights are turned
on).
Since the early ’90s, Honda vehicles have come with
an electrical load detector (ELD) unit in the
under-hood fuse/relay box. This unit allows the
ECM/PCM to regulate the alternator (switch it
between high output and low output) to provide the
best combination of fuel economy and electrical
system operation. The ELD sends a signal to the
ECM/PCM that’s proportional to the electrical
demand. The ECM/PCM switches the alternator
between high output and low output depending on
several factors, which include electrical demand,
battery charge level, and the driving cycle. When the
alternator is in low output, the engine load is reduced
and fuel economy improves.
If your customer complains about this flickering or
dimming, tell them about the ELD unit and how it
works. Unless the engine won’t crank, or the vehicle
has other symptoms of a weak battery, chances are the
flickering or dimming isn’t an electrical problem.

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I get the same problem in my 02 SE, 03 mazda tribute, and 03 miata. Just
electrical load on the system. Normal. I got it in my other fords and
mercuries before also.