Rep Power: 0

Good evening, I've got a bit of a dilemma and am hoping to use your experience. The other day the battery light came on. Today I grabbed an alternator and planned on replacing the old one. However, everything checks out ok so far with the potentially one exception.
I tested the battery with my voltmeter and it checks out above 12.7.
I cleaned the terminals aplenty.
Fuses are good and belts seem fine.
Alternator is 'magnetic' when ignition is on.
When at idle she's holding steady at about 13.5 or higher.
Prior to doing the 'load test' with the rpms above 2,000 it's @ above 14.
I loaded her up with everything on and it was @ 14ish.
But when the ac pump kicked in because defrost was on it went down to 13.5 then popped right back up.
Light is still on... I have an hour drive to work in Northern Michigan, in the dark. I don't want to bother with a towing bill! I'm thinking she will get me to work and back tomorrow before my favorite mechanic can dig in on Friday.
Thoughts? Thanks for reading!

 
Rep Power: 292

If the light just came on, I'd give it 2 or 3 days at most before replacing it.
If you really can't replace it, use a battery charger/maintainer to keep the battery topped off for the day.
Because for 90% of the drive, you will be relying solely on battery if the alternator goes.

 
Rep Power: 186

I'd take a couple of sick or vacation days and let your mechanic replace it ASAP if you're sure the alternator is your problem. I wouldn't risk driving an hour X2 with just the battery. You're just asking for trouble IMO.

 
Rep Power: 518

Anything else strange going on? Gauges acting wonky?



If you can't afford to be stranded, don't take a car with a KNOWN problem.

 
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Update... Nothing wonky other than the light here.
I kept a good eye on the battery and purchased a refurbished alternator. I then went to a VERY reputable auto electric guy. He looked it over and said go ahead and replace it. He pointed out the age and the fact that I had one ready to go, also the light was on for a reason. I replaced it and the light is still on. The next morning I went to work I noticed that there is a slight noise coming from the front where the alternator is... Kind of a belt woh woh woh, real faint (yes I did make it tight). Well that transfers to a flicker in the dome light when it's on, just a little flicker and not always there. I took it back into the electric guy and he said all seems fine and everything points to an issue with the Integrated Control Unit. He suggested I put in a meter to monitor it... I asked if he noticed the light flicker and he said no....but what I told him means that the new alternator has a faulty voltage regulator. Soooo I picked up another alternator and may throw it in this weekend. I'd like to avoid that if possible. I will attempt to tighten the belt first of course... Has anyone been down a similar road here?

 
Rep Power: 518

Discount parts store? The kind that is open on Sunday?

Did he say what the reason is?

The alt does not operate the charge warning light directly. The PCM, MICU, and the gauge module also have their say-so over control of that light through the data communication bus.
The PCM controls charging directly.



I MIGHT do some other troubleshooting......but I'd kinda expect to find the alternator is at fault (for the light, and it already sounded like it has a flaky regulator)


Did he do the gauge control module self diagnostic function test?
Did the charging indicator flash?

The service manual has a bunch of other testing you can do too....

Probably agree.

Sure sounds like discount reman parts.

I've seen the pulsating voltage regulator thing before on other stuff. (Discount rebuilder where price and profit is king, quality means nothing.)

This is why I like factory parts so much.




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Basic tests, paraphrased from the service info (and most of this was already done ??):

At 2000 RPM, is the voltage between 13.5 and 15.1V? (yes)
At 2000 RPM, is the alternator output over 60 Amps? (I'll assume yes)

Charging system is ok. (If the charging indicator is still on, replace the alternator.)

HTH

 
Rep Power: 0

Ha!
If only it could all be so simple! No, not discount... I know, I know I've been burnt enough times on aftermarket parts that almost all parts I get are original. ALMOST.. I kept thinking 'it's just an alternator' Guess I'm one of those people that keeps putting my hand on the wood stove. I also DISLIKE the Honda dealer in town here and figured time was not on my side.

I did not ask the electric auto guy all the questions that you mentioned. I just trusted him as he's done some great work for me. He did say that everything is working correctly and it all points to something wrong with the ICU. He also said that all the correct signals are going where they need to.

Thanks!

 
Rep Power: 518

Back in the olden days, we'd just unplug the harness from the alternator. If the light went out, that meant the alt was in proper control of the idiot light.


I don't have a 7th gen here to test theory on at the moment.....
but give it a try:
Unplug the 4 wire connector at the alt and see if the idiot light is out. (key on, engine not running)
If the light stayed out, just change the alternator again.


(If the light stayed on, that doesn't mean the alt isn't at fault, it would only mean my thinking is wrong. LOL)