No Charge Light - Low Charging Voltage

[11Budlite]

I was giving out rides to my niece and nephew on Labor Day and noticed that while driving the voltage was below 12 volts, not the 14+ that I usually see. With the car shut off and the ignition on, I noticed that the ignition light wasn't lit. I checked the bulb and it was still good, the wiring all seems to be in place and the belt is tight. The ignition terminal at the alternator lights up when you turn on the ignition and the B+ terminal is hooked up properly. Does anybody know what would cause the light to not be lit with the key on and the engine not started? It's a rebuilt alternator from a Geo that I got from Autozone. I think I have a lifetime warranty on it as well.

 

Thanks, Bruce :7frog:

[Al N.]

Bruce-

 

I'd post this over on the usa@se7ens.net email listserv...I think a bunch of folks who are more active over there (like Michael D.) have a lot of Zetec alternator experience.

 

Or look for Morgan's thread on here from a while back....when Mr. Orange's alternator crapped out on him....I think some folks had some expertise/experience they could share with you.

 

-Al

[11Budlite]

Thanks Al. I posted it on the Birkinowners list but not the usa@se7ens list yet. I'll be able to investigate it further tomorrow morning.

 

Bruce :7drive:

[Al N.]

Bruce, I did it for you this AM...hopefully some of the guys will come over to chime in...

 

Give my best to Nancy. Sorry I missed you up at LRP.

 

-A

[Cherik]

hey Bruce, good to hear you're collecting the miles! The season's getting short now... 55F and dropping rapidly...

 

Some ignition light stuff, that you didn't ask for:

The charge light has a few functions:

1. it connects the alternator field winding via the regulator (mounted on the alternator) to B+ when the engine is not running, but the ignition is on. When the alternator starts running, it's output will be equal to the battery, via the alternator diode groups. Then the difference between the alt. output and B+ is zero, and the light goes out.

2. it provides an indication that the alternator output voltage is lower than the battery.

3. it uses a 24V low output bulb to also act as a resistor to prevent the alternator from causing "after-run". It needs to be around 80..100 Ohms to work properly. If it's lower, then engine may not shut off... because the alternator field winding continues to feed itself from the small induced field and.. then things won't stop. An after-running cooling fan can cause the same.

 

Given the above:

1. alternator diodes went bad - this can happen when briefly shorting B+ to ground by accident with the engine running

2. bulb is bad, but you already checked that - but make sure it's a 24V bulb, not 12v (as that doesn't work properly)

3. the regulator went bad - if it was a rebuild it may have been compromised... good news is, Autozone carries diode and regulator replacements as I recall for Delco ( if that is what Geo uses).

 

Let me know what you find and I'll come up with more ......

 

Cherik

 

[11Budlite]

Thanks for the assist Al. Nancy says Hi!

 

Appreciate the help Cherik. I'm off to the garage to check some things out and maybe take the alternator back to Autozone to be tested. It's a Nippondenso alternator that was originally fitted to a Geo Metro. It's very compact and I think puts out 55 amps or so. I changed it from the original Bosch to move it to the intake side to get away from the exhaust heat. Here's an old photo:

 

http://www.usa7s.com/aspnetforum/upload/721282905_IMG_0861.JPG

 

Sorry I don't have a picture of the back with wiring connections. It has the main power B+ terminal, plus a 3-wire connector for the ignition, sensing voltage, and the charge light. I checked out the bulbs and they are 12V/40ma tiny little things that measure 31-32 Ohms. Here's a bad photo of the bulb. Don't think I've ever seen one like it before:

 

http://www.usa7s.com/aspnetforum/upload/1241235318_20080906_0001.JPG

 

I'll let you know when I find out more.

 

Thanks, Bruce :7drive:

 

PS: I'm going to need some great weather for many years to catch up to you Cherik!

[11Budlite]

Well, I took the alternator to Autozone to be tested. The guy couldn’t tell me what was wrong with it, but he could tell me it was NG. Any alternator problems that I've had in the past have been with the diodes so if I get a few extra minutes tonight I'll check those. The new alternator should be in tomorrow (no charge) so I'll soon be back on the road!

 

Has anyone ever seen a bulb like the one above and do you know where they're available? I forgot to take it with me when I went to the parts store.

 

Thanks, Bruce :7drive:

 

PS: I found a nice explanation on alternators here: http://www.autoshop101.com/forms/alt_bwoh.pdf