So I am working on a older GM product today. 72 olds to be exact. But essentially the same from 64-72 from what I am told. Someone else couldn't fix it. Now it's my turn! I have rechecked all the connections and as far as i can tell they are correct. It has a new engine harness, New alternator, and a new external regulator. All replaced at the same time, due to a hacked harness and a bad alt. With the new parts installed It's charging at 22 volts. what the hell is going on? I am ***uming that the Alt is getting "full field" Where do i even start testing? I've done some googling but I haven't found a for sure way to test the regulator. but I have tried the new and a random untested one. Both the same. I've got continuity between the alt. and the reg. on the field wire. I'm confused and don't know where to start. Any help or a link to how these cars are wired would be great.
Does the alternator quit charging when you unhook the two wire plug? If not alt is bad, maybe short from bat to fld internally. F and 2 wires should run between the alt plug and reg and no where else. 3 wire should power with ign, seem to remember 4 wire works the light. Easy to hook up alt to reg to ign with jumpers to eliminate harness. Also I once had a defective battery that made the alt charge at full rate.
Flags go up when new harness is mentioned. I had a mid 60s GM truck that had some sort of charging issue, but I don't recall what... anyways, there was a small difference in the underhood harness and main harness on gauges vs. idiot lights. The truck had one mismatched harness from the other style, and as I recall it was a wire not in the right place on the bulkhead connector. So, I'm just saying that you should not ***ume the wires are correct. If I was doing it, I'd get out the wire diagram for it, or one from Motors manual, and use temp jumpers from alt to reg, ... or unplug the alt and reg and check each wire function with key on, to see if they seem ok.
The best way to check is put volt meter across battery should read about 12 volts,now start it and see what you read, if you read 22 get another alt.
This diagram might help, (mid sixties C10), does this Olds have to be stock or how about a conversion to a 10si alternator http://rmcavoy.freeshell.org/diagrams/66engine_8.jpg
I did not think that a alternator would charge withthe two wires disconnected. Nothing to excite the field hence no charge. Take the alternator to a parts store and have them check it or swap it out with one that you know is working. I would change the battery also and eliminate the wiring by running seperate jumpers and then see what you have.
The first thing to do is verify that the previous mech installed the correct parts. I'm betting that there is a mistake in the new parts or the new parts are defective...it happens. Anytime someone else has been into it you have to go back to zero and ***ume nothing. The first thing that comes to mind is that the new regulator is not regulating. You need a Motors manual from that era to determine the tests that you need to take to figure out the problem. Follow those steps and you will find out what is wrong. There are tests for the regulator and for the alternator. Without these tests you are just throwing parts at it. JMHO
People always pick on me when I convert to a single wire self exciting alternator.....I do it because there are less things to break.
What brand of harness is it? It's possible two wires were switched at ***embly. I've seen offshore stuff wired backwards a few times. Grounds. Check all grounds. Make sure no paint blocks the path of current. A sulphated battery will read high like this, check with a hydrometer. Fluid should be clear.
If it still charges with plug disconnected, the alternator is the problem. Take it apart and see whats wrong, those are pretty simple units.
Actually and this is just a 'bean thought I think that is a wive's tale. Now before you get involved in what a dummy you are her is my reasoning. For years I ran 1 wire alternators without the jumper, infact the first vehicle I ever had a jumper wire in was the Pusher in '04. I never had a charging problem and that's a lot of years without the jumper. The only real difference between the 1 wire and the older external reg is the placement of the regulater. Well I guess the type of regulater but never the less the concept should be the same. Perhaps we can file that under ignorance is bliss. Anyway back to the original question I don't know if anyone has hit on this but it may just be that the regulater is out of adjustment. Most of the GM regulaters that I have fooled with over the years were adjustable. The alternater puts out what it puts out, it is the regulater that determins how much zot gets to the battery. Someone mentioned that the charge should be checked at the battery with a volt or multi meter. I agree with that. A few years back I had an alternater that was charging 18 volts all the time. I ***umed that the rugulater was bad and it was a good excuse to go through the alt and uprade it. Done with that and I had the same problem, it was then that I decided that checking at the battery with a Volt meter was a good idea. Long story short my newish VDO gauge wasn't reading correctly. I ultimately went through another 2 gauges before I found one that read correctly. Well that's a lot of words for very little information. I hope you get it sorted out.
Just an update....It ended up being a bad new alternator and a bad hand held volt meter. It wasn't charging as high as I thought but it was still overcharging.
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