Alternator Advice - '91 Civic Si

Hello,

I was on a trip back to my home on a 2-lane highway tonight, and I was
about 50 miles out when my charging system warning light came on my
dash. I made it home with no incident. I had to have my headlights on
because it was dark. I cut all my other accessories when the light came
on and for the rest of the trip. The car has around 140k miles and I
don't know the history of the alternator on the car before 120k miles. I
am assuming it is the original. I got a new battery in the fall (autolite).

The light came on flickering originally, and then stayed constantly lit.
When it first stayed lit, it stayed that way for about 25 miles. It then
went on and off for the rest of the trip home. The light seemed like it
would go on or off either when I was reving up and accelerating leaving
a small town (25 mph speed limit on the hwy.), or shifting in to neutral
and coasting into a town. The light wasn't contstantly going on and off,
it tended to stay one way for atleast 5-10 minutes. The weird thing is
that before the light came on for the first time, I experienced a
fluctuating idle from 750-1300 RPM when I was coasting towards a red
stoplight in a town. I don't think I have air in my coolant, and I have
no idea weather this would be related or not. I had an idle fluctuation
last fall, but I did an air purge and it seemed to fix it. Coolant level
has not noticeably dropped.

I am looking for cost effective/reliabilty advice. I see Majestic sells
reman. alternators for about $170. I don't know what all would be
replaced in them, and maybe I should just call and ask. I guess what I
am getting at, is that it seems it is fairly cheap to replace the brush
assembly. I didn't hear my bearings go and I looked at my belt and it
seems fine. I figure I could replace the bearings anyways as preventive
maintenance and do the brushes. Does the rectifier (diode assembly) last
forever? Would a reman. have a brand new rectifier? I think I could
handle the work involved with doing the brushes and bearings, but I
guess I don't know how to proceed. I am thinking of taking the car on a
serious trip in the future (midwest to west coast USA and back), and
wouldn't mind spending a little more for piece of mind. I looked at the
alternator tonight, and based on where the electrical connector plugs in
it looks like a Nippon Denso. Thanks for any and all advice.

Mark

 

Another note or two:

I always noticed since I got the car that the headlights dim under some
circumstances, but I can't think of any specifics as to when this
occurs. The ground cable from the battery is old and a little green in
spots, but when I grab it and bend the wire arround it doesn't seem
severely corroded. It seems largely intact. I never have problems
starting the car (except when I gave my old battery the finishing blow
last fall by shorting it with a combination wrench, Doh!).

I guess I should check the diagnostic procedure in my Helm manual, but
I'm thinking my charging light came on because it is the alternator.
Unfortunately my multimeter is MIA.

Mark

 

I drove the car today during the day today to go grocery shopping
(around 5 miles round trip) during the day and the charging system light
did not come on. I took the car for a 10 minute spin around town
(mixture of highway and city streets) later when it was dark out with
the lights on and the light only came on a couple times. I am starting
to think my alternator may be okay, but it is actually the Electric Load
Detect (ELD) unit which is in the main fuse box under the hood (USA
model). My idle has been behaving more strangely than normal, as in it
oscillated a few times when I was in neutral at different stopping
situations, and as in it wouldn't return all the way down to ~750 RPM
sometimes. Using my brakes has always caused my idle to drop a little,
but I figured this was because my power booster is a little sloppy.
Maybe most of my idle issues relate to my ELD being sketchy.

My No. 14 fuse in the dash fuse box is fine. It looks like the ELD unit
is integrated into the main fuse box. I think I'll try to check it out
tonight, because I got mixed up and I do have my multimeter, but not my
soldering iron.

If anyone has had problems with their ELD I'd be curious to hear what
happened.

I'll probably go for another cruise tonight to see if I can get my car
to yeild some more symptoms, or at least repeat some I've already
experienced. I hate to go out and buy a new (rebuilt) alternator when
its not the problem.

Mark

 

Okay,

So here are the results of checking my ELD unit according to the Helm
manual:

With my ignition switch on, and the 3-P connector detached from the ELD
unit:

There was between 12 and 13 volts (don't remember exactly what the
voltage was) between the BLK/YEL (+) and the BLK (-) terminals on the
3-P ELD connector harness. Seems okay, I'm not sure exactly what
'battery voltage' (what the manual specifies) should be.

There was only 4.56 V between the GRN/RED terminal on the same connector
and body ground. The manual states this should be aproximately 5 V. I'm
not sure what the tolerances are, so maybe I should follow this lead
(check alternator control system).

After reattaching the 3-P connector to the ELD unit:

I checked voltage between GRN/RED and body ground with my headlights on.
It is supposed to be aproximately 2 V and was about dead on.

I could redo this tonight or tomorrow and do a better job recording the
voltage readings. The 4.56 V is exactly what I read for that particular
reading however, and I made sure I memorized the reading because that
one seemed off, if any of the readings are.

The Helm manual says to go to sec. 11 for the alternator control system
check. This looks like ECU headacheville where I may need an ECU test
harness. The troubleshooting guide in sec. 11 (Fuel and Emissions) says
that irregular idling, when warm RPM too low can be caused by ELD. I
failed to mention this previously, but within the past few weeks there
were a couple of instances when my idle dropped significantly below ~750
RPM at idle, but it never stayed consistently that way at subsequent
idlings.

I think I'll take a break from this for today. Luckily I don't have any
major out of town trips planned for the immediate future.

Another addition of information:

My check engine light is not lit, and it, and my charging system
indicator lights botch come on normally (and the CEL goes out after a
couple of seconds) when I turn the key to the on position.

One last thing: According to the troubleshooting guide in section
eleven, it looks like the LED on the ecu can flash a code for the ECD
withouth the CEL being on, so maybe I'll pull up some carpet tomorrow
and have a look.

Crap, one more question. Can the grease thats packed into the plastic
electrical harnesses cause shorts if it is oozed out the back of the
harness, and seemingly connecting the various 'cells' of the harness?

Hoping to get some tips,

Mark

 

the two obvious suggestions to check are loose connestions & loose drive
belt. other than that, it can be fairly random the life you get from an
alternator. my 230k civic & my 304k crx were/are both on original
alternators and no sign of any weakness.

has the car had a bad oil leak or been pressure washed? both could be
potential sources of problem also.

regarding rectifiers, yes, they're replaced on rebuilds. you can
replace them yourself if you're so inclined, but it can be apita. no,
they don't last forever. any semiconductor has finite life as a
function of current flow & operating temp. the question is "how long".
if you get into the habit of keeping electrical load down, they should
last the life of the alternator bearings at least.

and the bearings on honda alternators are fairly good in my experience -
unlikely you'll need to replace them. if you can conveniently replace
the brushes, that's a good thing. anything else, i'd just go for the
re-manufactured unit.

 

I don't now if anyone's still following this thread, but I think my
charging system warning light may have come on because of a poor
connection between the 3-P harness and the ELD unit in the main fuse box
under the hood. Ever since I performed the diagnostics on the ELD, the
light has not come back on. I took one good drive after the diagnostics,
and the light never came on. Tonight I separated the connection again
and used a pick to scratch up the surfaces of the pins that meet in that
connection and scraped out as much of the old grease as I could. I then
squeezed some permatex dielectric grease into the connector from the
rear where the wires come in as best I could and removed the excess.
I'll be taking the car around town on some short trips this week and
I'll report back if my indicator light comes back on. This may have just
been an intermittent electrical connection issue.

Mark

 

Just did the brushes and bearings on my
girlfirends 87 prelude. Her problems started out
as an intermittent lighting of the charge light,
and eventually lead to a dead battery. If I am not mistaken, your
alternator is internally
regulated, the 87 prelude was externally
regulated.

Total cost, about $10. Its pretty easy to check
to see if your brushes are in spec or not.
However, an impact screwdriver is nice to have to
get the flange bolts off to separate the stator
and the back part of the alternator. My Haynes
manual had a pretty good description of what
needed to be done here.

Bearings I got from a local bearing shop, mine
were 6202/2RS for the rear and 6203/2RS for the
front one (yours may be different). To do the
front one, you need impact to get the pulley
off. The bearings retail for about $5-9
depending where you get them. Go for the higher
quality ones (made in Germany or Japan, not the
ones from Korea or China)

The brushes I acquired from a local auto electric
shop for $3. Brought in the old worn out one,
and he picked one of the same size off of the
shelf. Honda may sell these separately as well,
though I doubt they would be any higher in
quality, their just graphite with a copper wire
hangin out of them, aren't they?

Put it all back in, and no more problems!

t

 

It's the brushes! You can get an entire new brush holder assembly from the
dealer for about $20 and easily fix it yourself with the alternator in-
situ.

 

I did have a similar problem on my 85 Nissan
200sx, cleaned the contacts and replaced a few
wires, but eventually lead to symptoms of a
bigger problem, the alternator was toast. At
the time I did not have the experience or desire
to try and rebuild it, but rebuilding is
definitely the way to go if there is no damage
to the stator assembly.

How hard is it to get the alternator out of your
car to take it in for a test? I had to pull a motor mount to get it out
of the prelude.Though
I am not a big fan of the testing machines, they
do provide some info, and you can put your
multimeter on the alternator while the test
machine is spinning it up, to see what the peak
voltage is.

t