I just picked up a 72 Cutlass with an Olds 403. Drove it from North Carolina down to Georgia and she did well on the drive but I felt like the starter was pretty tired and would need to be replaced soon. When I got home I popped the hood and smelled a boiling battery. Pulled her into the garage and when I shut her down, the GEN light stayed on and won't go off. Goes off when I start the car but when it is off and key is out it is on.

Took the battery and Alternator to get tested today and while the battery charge was low it tested good (surprised me) at three different shops. The Alternator however failed tests. I bough a new alternator and hooked the battery up to charge. Got the new alt installed and reinstalled the battery and she fired up. When I shut her down the GEN light is still on. Is this because the battery isn't fully charged or is there still an issue somewhere? Forgive my ignorance but I am unable to determine if I have an internal (in the alternator) or external voltage regulator. Could I have a bad reg?

One other thing to mention: When I picked the car up I was surprised that the AC blower motor wasn't working when I got there but I found that the AC fuse was blow. Changed it and AC works fine now. Could be unrelated but figured I would mention it.

Any help for a novice willing to learn would be greatly appreciated. Thank you all.


update: I went to take the trickle charger off the battery before bed and when I touched the alternator, it was hot to the touch. The car hasn’t run for about 5 hours so it has cooled down. Not just warm, it was quite hot.

update 2: I read about a buzz on the stereo being caused by a bad voltage regulator and there is a buzz in the stereo. I’m hunting for the regulator now.

 

Did you replace the voltage regulator? Could be the culprit.

 

I haven’t. I wasn’t sure if it had an external voltage regulator or was internal in the alternator. Do you know where the regulator would be located and what it looks like?

 

If it's external regulated it would be on the firewall.

 

I went to take the trickle charger off the battery before bed and when I touched the alternator it was hot to the touch. Car hasn’t run in about 5 hours so engine is not hot.

 

Pictures in this thread:

https://classicoldsmobile.com/forums...outing-161430/

 

Ok, I am nearly positive it is the voltage regulator. I just need to track it down now. There was mention on that thread about hearing a buzz in your stereo and there is a buzz in the stereo. These pictures help so now I just need to follow some lines and track it down. Thank you for your help. I’ll update as soon as I have any news.

 

You might review the diagram I posted here, as well - I list the two VR part nos.

Post >>> 4

 

This is what I am seeing under my hood.




and this diagram doesn’t show a voltage regulator anywhere and I can’t seem to find one either. Any help on locating this elusive voltage regulator would be very helpful. I am fairly confident that is my problem but I can’t fix it if I can’t find it. Thanks all

 

These two gold color guys at the top are the defog relay and AC relay (I think) but no voltage regulator to be found.

 

Ah right. So, I "think" you probably have an internal regulated ALT - VR contained in the ALT. The reason I mention this is because you said you have a 403 engine (not available in 1972) - the 403 was 1977-1979. With that said, it's likely, not necessarily true, but most likely the case you have an internally regulated ALT. What I'm trying to say is there's a "chance" an external VR could be located elsewhere (since your engine is a transplant) and won't follow the normal 1972 OEM standard locations. Most likely guess is the ALT has an internal VR. A picture of the alternator would help. Since we don't know how the engine was wired, you'll have to do some digging.

 

Ok, I think we are making a little progress. This is the alternator I replaced the old one with last night. It has an internal VR

https://shop.advanceautoparts.com/p/...-3av/5030250-P





I am going to contact the previous owner and see if he can direct me on how he wired it when he put in the engine.

 

Yes, make a little progress. Good deal. Knowing you have an internal VR ALT mounted to a 403 in a '72 is going to assist greatly. I don't have the knowledge to assist you in identifying/diagnosing/troubleshooting your particular situation but others (especially the original owner who performed the transplant) will have to provide you w/ more pertinent information. Others on this site have far more knowledge to help assist you. Good Luck!

 

That's OK. I don't know what it is. It looks like a more or less standard type in-line fuse (of some type) - has red ends (both ends) indicating a positive power cable, aside from that I don't know. Can you trace the wire this device is inserted into? It has to have a beginning and and end point. Looks more like an in-line fuse I've seen on a marine application, but all this is not bad. You're going to struggle a tad trying to identify the wiring since you now know what you're up against. Good time to get a notebook and start making some drawings with notes on wiring.

 

It is part of the wiring harness for the amp (stereo) in the trunk.

 

I'll just point out one thing I noticed from your statement. You said you replaced the old one (alternator) with this new one. Are you CERTAIN the old one (ALT) was internal VR or was it external VR? That in itself is going to be significant in terms of wiring. You have a picture of the old alternator?

 

Then it's nothing more than an in-line fuse (most likely) for the amp electrical. Doubt it's an in-line breaker, most likely just an in-line fuse (of some amperage rating).

 

EDIT: I'll point out in case in the future you have an issue with the stereo amp, that type in-line fuse should be able to be opened by unscrewing it from one or both ends. Inside you should find a circuit protecting fuse (of some amperage). You won't hurt anything if you want to open it up and review it yourself. But knowing what it is will help in case you do have an issue with amp electrical in the future. If the fuse ever blows you'll know where it (at least this one) resides.

 

old alternator





sorry, uploaded wrong pictures at first.

 

Googled one of the part numbers. Pretty sure this is the old alternator.

 

Yes, I found both alternators - they're both internal VR. Therefore, the ALT is wired with no external VR. Again, this resides outside of my wheelhouse regarding knowledge on how that ALT is wired on a 403 sitting in a '72 A-Body. The PO or others on this site will be able to provide more additional assistance to you. Good Luck! Do start writing down some wiring schematics in a note book for future reference.

 

ALL 1972 Cutlii left the factory with an external regulator and the one-year-only alternator that looks like a 12SI but isn't. If this car does not have an external regulator charging system then someone changed it. We have no way of knowing whether or not they wired it correctly for that conversion.

 

I don't believe there were any 1972 Cutlii which left the factory w/ a 403 or am I mistaken?

 

The engine has nothing to do with the charging system.

 

I understand this. I'm only providing credibility as described in my previous posts regarding the type of ALT which the OP originally believed was an external VR system. Aside from this, the "issue" is apparently the Gen Light remains ON. So, I'm not certain what may be the underlying issue other than most likely wiring of some type. I believe the OP is reaching out to the original owner who I suspect dropped in the 403 and performed the wiring. Thanks.

 

And my point is that if the wiring to convert to a 12SI was not done correctly, the GEN light will stay on.

 

The GEN light will stay ON when the vehicle is OFF if the conversion to a 12SI was done correctly? Interesting.

 

Evidently I'm having a moment as I was pretty certain the original post didn't contain the word "not".

Think I'll pick weeds the remainder of the day.

 

With car off, battery connected, key out of ign, does the gen lite stay on? If it does, pull plug out of alternator and see if the lite goes out. If the lite is off with plug out, test the wires in the plug while it is disconnected. The heavy red one should have voltage and the other should have none. I suspect these wires are reversed somewhere. If so it would cause all the symptoms you have mentioned, being over charging, lite on with key off and alt hot after sitting.

 

Alright y’all, I figured it out. I drove it from NC to GA and during that drive the alternator went bad (in particular the internal voltage regulator). It was sending 16+ V to the battery which during the 4 hour drive got overcharged and boiled. There was a 12ga wire run to the positive on the battery which ran over the the power distribution post on the fire well. That wire got too hot and melted causing a couple other wires to melt and short together.

I replaced the alternator and fixed the burned wires and all has been well the past three days. I’m watching the wires and voltage but everything has been good to go.

thank you to everybody who helped and posted. This gave me some direction and confidence to start digging.

 

Suggestion: Purchase an inexpensive voltmeter that inserts into your cigarette lighter. For times when you suspect something is amiss it is a very helpful tool that displays your voltage output via a digital display while driving.