1995 302 battery light on low out put from alternator

[Yell0wB055]

Hi all I am looking for some help tracking down a problem with my electrical system. I had a friend replace the harmonic balancer in my car and when he returned it the battery (alternator)light stayed on constantly. I have tried new battery, replaced 3 alternators, DVM to check wiring for resistance and when I pull regulator wire off the light in the dash goes out. Output of the alternators is about 11.6. Checked the ground and connections for continuity and I am at a loss as to what to do next besides replacing the CCRM.Any ideas would be helpful.
Thanks!

 

[desertcox05]

output at the alt should be 14.2-14.5

 

[Yell0wB055]

output at the alt should be 14.2-14.5

I agree. The Alternator tests good off of the car and drops output when on the car.

 

[cbarr300]

Check and double check all your connections

If you have any powdercoating on your brackets, sand it off where the alternator meets.

Check your fusible links in the alternator to battery power wire

do a search and you'll find some great information by JT (hissin50)

 

[HISSIN50]

Clay is always too nice to me.


FWIW, the CCRM is not your issue.

When you remove the alt's reg plug, you remove the grounding pathway from the battery light. This is why the light goes out. Your alt can't possibly function this way either.


Resistance checks in alt wiring are all not efficient, nor helpful.
Do some quick voltage checks. The regulator is labeled A, S, I (the letters are embossed on the reg).

A is battery voltage. If this is missing, check the alt fuse in the underhood fusebox.
I is the signal to turn the alt on. It should show 1.0+ volt while the car idles.
S should float about 1/2 battery voltage.

The one time resistance/continuity checks are useful is to check the S circuit if you have an issue there. Disconnect the reg and the little lonely plug and check continuity between both wiring pigtails (S and the lonely little guy). You should see about 1 Ohm or less.

I would really inspect the fusible links that Clay noted. Maybe a wrench hit something while doing the balancer (not accusing anyone of anything but I often try to think of what someone could have done while doing an R/R). The links on my car were on the driver's side of the PS pump housing, just before the cable goes to the PDC (underhood fusebox).

In general, check the wiring harness as it leaves the alt. The insulation can vulcanize and the wires break, short together, etc. If you have to 'chip' the wire loom off, expect to find vulcanized wiring underneath. It's a hot climate and underhood heat thing.

I've covered this stuff in greater detail before (you might find more detail in other posts) but this is the broad strokes.

Good luck.

 

[cbarr300]

look at that...you didn't even have to search

JT: I always recommend your info to peeps. I couldn't tell you how many times I've searched through the forums trying to find information to get me back on the road when I first started messing with cars...only to come upon your old posts. That alternator issue I had was driving me crazy...

 

[Yell0wB055]

JT & Clay I really appreciate the info and that was so quick. As you can imagine this has been enough to pull my hair out over (I do not know how to trouble shoot electrical issues well) I have plenty of new options and you stopped me from investing $160+ for a new CCRM. Thanks again for taking the time to help me out!
Dave

 

[cbarr300]

no problem at all...always better to research and diagnose rather than throw parts at it.

Being that it started messing up after someone worked on it it's possible the alternator lead somehow touched ground (though I don't know how it would do that since you don't need to take the alternator off to change the balancer). You never know though, mistakes happen...ask me how I know, lol.

good luck on it.

Nice car btw

 

[FlyBy763]

Does the light stay on no matter the RPM of the car?
Dont take the alternator testing good off the car as meaning it is good. I had an alternator test fine on the bench and end up being the problem, whether it was the regulator or alt.

 

[Yell0wB055]

Woo Hoo!! Problem solved. Thanks to your suggestions I am back on the road Brothers!! JT I was going to go straight down the list after a quick eyeball for the powder coating on the bracket and fusible link Carl suggested (Thanks Man!) and the first thing on the list was A for battery voltage then check the Alt fuse under the hood. Well I found a nice diagram online of the under hood fuse box and printed it out then on the way home for lunch I found a 20 amp & 25 amp fuse just laying in my sport console of mu Buick and put them in my shirt pocket in case I needed them later then I said a big prayer before I pulled in the driveway (that always helps ) And as I said I popped the hood and took a quick glance around and decided to just look at the Alt fuse before I even got out the DVM. Guess what?? there was not even a fuse in that spot!!! I grabbed the one out of my pocket and plugged that baby in and it started right up !!
Thanks again !!

 

[cbarr300]

That's great news man!

That fuse not being there will def. cause a no charge issue.....that seems kinda fishy to me though...someone had to have taken it out for some reason

Me thinks someone somehow had an accident while trying to change your balancer.

If you have any other issues just let us know

Clay