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[Help!] Battery not Charging Problem

46K views 42 replies 17 participants last post by  CTSvOH 
#1 ·
So, the V is currently apart. My attempt to chase the battery not charging problem. I got a pigtail for the alternator flat connector (4-pin, only two middle pins used). Now, before I splice that in, I'd like to see if you guys had any idea what could be causing that problem.

Background. Battery is healthy (12.98V measured just 15 minutes ago) and the engine cranked/fired just fine. All other systems in the car are working properly. The car has stock electronics other than disabled DRL, OnStar and XM radio modules. Driver side engine mount is shot.

The problem started with intermittent "Battery not Charging" message. In the beginning it was rarely displayed so I dismissed it. The frequency and the period increased over time until this past Sunday and the message stayed on solidly (along with the battery light). I thought I might have noticed that when the engine is revved, the message disappeared. I might be wrong on this last point; please take it with a grain of salt for now.

Monday night, I tore into it and took out the alternator. Advance Auto Parts tested it and said it's working just fine. So, the alternator is healthy and is not the culprit.

I moved to the next item. Alternator/battery cables. After disconnecting the one that went to the fuse box under the hood, I measured the resistance between the terminals (alternator terminal and fusebox/battery terminal). Resistance did exist (0.2 ohm). So, it's not the battery or the alternator cables.

The only thing left is the flat-4 connector that plugs into the alternator. What does it do ? If they were to be disconnected or severed, would the DIC think that battery is not being charged ? OR, would the system overcharge the battery ?

This connector has two short wires coming out of a big bundle. Taking the consideration that the engine rocks (likely more than normal due to busted engine mount) when revved, it is possible that the two little wires were pulled to the point that electrical contact was compromised or maybe they were frayed although I could not see anything on the exterior suggesting that they were damaged.

What should I do ? Go ahead and replace the connector with the pigtail (providing more slack too when the engine rocks) ? What if it didn't solve the problem ? What could possibly be the problem if it's not this connector ?
 
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#3 ·
How does Advanced Auto Parts test alternators? It could be breaking down under heat and could still be the culprit.
 
#6 ·
I had this when the car was under warranty. Dealer eventually fixed it but it turned out to be a wiring harness. I can't remember for the life of me which one it was. It may even have been the PCM wiring. The message is triggered every time voltage slips below 12V when car is running for a period longer than 10 seconds or something similar. Had a tech look it up.

Have you tried disconnecting battery when car is running? This will rule out alternator.
 
#7 ·
I really hope it's not PCM wiring. I'd just part out this car and chalk it up as a big fail in my life.

If you still have the service receipt, it's probably mentioned there.

No, I have not tried disconnecting the battery when the car is running. However, alternator is already ruled out.
 
#8 ·
:bigroll: Because Advance Auto Parts ran the alternator up on the bench, does not mean 'jack'. Because the alternator was not taken apart and an inspection & test of the individual parts ie., stator, rotor, slip rings, rectifier bridge/diodes, brush holder, brush springs & brushes,and the likely culprit the internal 'voltage regulator' was not performed, then, it should NOT be assumed that the alternator is not the problem. I always take the alternator apart and rebuild it, but that's me.:yawn:
The internal 'voltage regulator' can be an intermittent problem when beginning to fail. The "regulated votage" can be affected by the ambient temperature surrounding it.
So, that's my story ~ speaking from experience. :wisdom:
Hopefully it is not more serious.
good luck.:)
 
#10 ·
Now, if any of those parts you mentioned had failed, wouldn't it have showed up somewhere on that test bench ? They did put a load on the alternator during the test and it passed. The test didn't just spin the alternator and measured the voltage between the terminals.

I can always start throwing parts at the car but it seems unwise. That's why I had the alternator tested. Now, I can bring it to a couple other places and have them test it too.

Another thing is there is actually a thread (showed up on my search) that showed the same symptom(s) and it was not the alternator. ichpen indicated that his problem was due to PCM wiring harness.

Please read my original post again. I indicated that by the time before I removed the alternator, the Battery not Charging message was on solid. No amount of temp difference or whether the engine at low, mid, or high rpm made a difference.
 
#11 ·
I re-read your post.
Question: After you had the alternator tested, did you put it back in the car and 'fire it up' to see if it was charging?
It would be easier for you if the internal voltage regulator was 'on the blitz'. When they start to fail, they turn 'on' & 'off' randomly and it can 'drive you up a wall'.
There are two brushes in the alternator that ride on the slip rings of the rotor. If one of them 'hangs up' and then, frees itself, that would cause an intermittent, but I doubt if there is a brush problem.
Hopefully it is not the wiring harness. That sucks, man.
:yup:Good idea to give a little slack to that connector, cause if it's not connected, it's not charging.
good luck - keep us posted :thumbsup:
 
#12 ·
The car is still apart and no, I have not tried that. I was/am hesitant to cut off the alternator connector and splice in the new pigtail. That's why I created this thread; hoping that someone may shed a light on it before hacking into anything.

If it was indeed the voltage regulator, I would have thought the voltage would have been outside the limits when tested, no ? Do you know for a fact that if the 4-pin connector (one or both wires) isn't properly connected, the alternator won't charge ?

Maybe this weekend after the race, I'll just suck it up, cut off the connector and splice in the pigtail :stirpot:
 
#13 ·
Fact: The two pins being used in the connector is the 'L' & the 'F'.
Voltage is supplied though one of those wires ( L terminal ) to turn on the regulator. That voltage in that wire comes from the PCM. So, the PCM turns on the regulator. The voltage regulator controls current to the rotor by switching 'on' & 'off' at a rate of 400 cycles/second. At low speed, the 'on' time may be 90% and at high speed the 'on' time may only be 10%
.
If you turn the ignition switch to 'RUN', there should be current to the 'L' terminal that comes from the PCM.

The 'F' terminal is connected to the voltage regulator and the PCM monitors the 'field' voltage.

I will admit, that I have not had a new (since the '90s) alternator apart, but the technolgy of alternators has been the same since the '60s.

So, if that connector has a poor connection, your alternator will not function properly and your computer will message you.
 
#16 ·
FYI ... I had an alternator checked at Autozone, O'Reilly's and NAPA, each time passing their test.

After each test, I reinstalled and had the same charging issues.

Replaced the alternator and charging issue went away.

Operator error when testing alternators seems to be a real issue.
 
#17 ·
More development. More info.

Well, tested the alternator at O'Reilly and it passed.

I took a voltmeter to the connector, switch the ignition key to on and this is what I got.

The gray wire (F terminal I believe) is grounded.

The orange wire (L terminal) has 0 volt.

So my wiring is screwed up, right ?
 
#19 ·
Make sure the terminal and the wire have a good connection to each other. If you measured 0v at the wire terminal, it is possible that the terminal and wire have a poor connection. How does it look? Is is it oxidized? Check further back on the wire. If you pinprick the wire, try to seal the pinprick hole, so it does not oxidize at that point in the future.
 
#22 ·
Since obviously your alternator is charging, it's probably the gray wire that got frayed (in my case it's the orange wire). That's the wire that monitors the alternator output. The outside/jacket of the wire did not indicate that it's been damaged inside.
 
#23 ·
I'm having the same intermittant problem since last week. Flashes on my DIC that battery isn't charging, battery light comes on. Then it shuts off by itself. the battery light will turn on and off intermitantly, no real consistency. If i'm on the highway it doesn't seem to be as fequent, maybe heat related.
I shielded all wires away from my headers(no obvious sizzling), and unplugged and reseated the alternator orange/gray connection.
My battery voltage seems fine, and plugging it into a charger it seems relatively full charged. I even hooked the battery while the car was running and the car will still run. I'm going bat shit trying to figure this out. Where abouts was your wire frayed? So if my alternator seems to be charging it should be the grey wire?
How long am I safe to ignore it?
 
#24 ·
I cut the wires about 1.5" from the connector and I got good solid signal. I wouldn't guess where it may have been frayed as the jacket looked fine or maybe it's just not making good contact with the terminal.

The gray wire, I believe, is how the PCM reads the field voltage as described previously by Stepside. If your battery got charged just fine, it's probably just the gray wire. See if you can wiggle it and have someone watch the light/navi screen.

I have no idea how long you got before you have to do something about it.

One question, do you have problem with motor mounts ?
 
#25 ·
Thanks for the insight. I have had poly mounts in my car for awhile, but I did have broken mounts last summer when I bought the car, they were real bad.
I did pull that plug when the car was running, the battery light came on and the voltage on the DIC dropped to 12V+, I imagine thats's about what the actual battery is without the help of the alternator.
 
#26 ·
Thanks for the insight. I have had poly mounts in my car for awhile, but I did have broken mounts last summer when I bought the car, they were real bad.
No problem. I'm starting to wonder if this type of charging problem is initiated by broken motor mount(s). These two wires are quite short coming out of the big bundle and the excessive engine movement put extraneous pulling.

I did pull that plug when the car was running, the battery light came on and the voltage on the DIC dropped to 12V+, I imagine thats's about what the actual battery is without the help of the alternator.
Mine did the same. When the warning light is on, battery voltage would drop to just about 12V and then it would bled off fairly quickly depending on electrical load.
 
#27 ·
Okay so I plugged in my code reader and it says p0621 generator L-terminal circuit, I haven't tested the volts on it yet, but it appears that it is the same wire that was the culprit on yours, the orange wire. Previously when I unplugged the circuit I had both p0621 and p0622 history codes for both circuits. I had wait for the light to come back on so I could read it again.
Did you reuse the stock connection but splice in a new length of wire? or just discard the connection all together? I hope mine is frayd at the connection like yours and not half way up the wiring harness or something dumb like that.
 
#29 ·
Well I replaced the connection, cut off about 2" of wire and still the light came back on, so I'm not sure P0621 means the alternator is on it's way out or not. I volt checked the wires and both have power when the light is off. It's seems my alternator is charging the battery, according to my display voltage it never drops when the battery not charging light comes on, so i'm confused. I either ignore it untill/if my alternator fails, or start shopping for an alternator. Or try tracing back the wiring to the fuse box and run a whole new set of wires?????
Jiggling wires seems to do nothing when the light is on, man I'm going nuts.
 
#32 ·
No not yet, aside from pulling my battery cables and the car still runs, and the dic voltage remaining constant.
First i'm going to make sure all alternator wires are well away from my plug wires, I know some are close, and I have NGK iridium plugs. Then I'm going to check and retighten the alternator main line to battery connection, seems secure but I never removed it. I'll also try unplugging my horn and see if that works.
If none of the above works, I'll get my alternator checked.
If it checks out, the next time I get a tune I'll get the code shut off, it maybe just an ecm tune glitch like stated on the corvette forum.
 
#33 ·
I had this same problem the past few weeks, until it finally died. Props to the fellow who spoke of checking the orange wire for voltage when the key is in the on position. This led to 0 volts on the connector in this position versus 11-12v about 1 inch past the connector on the wire where i peeled the orange wire back a little. All I did was simply pop out the connector pin from the connector and resoldier a wire onto the connector pin, pushed the pin back into the connector and then resoldierd the newly soldierd wire and pin to the factory wire (which is really short) from the wire harness. Everything is back to normal now.

For those of you that are getting this message and your battery is still charging, but says it is not. it is most likely the gray wire that has lost its connection not the orange wire.

Cost to fix = $0
However I ordered a new alternator anyways, guess Ill have to return it.
Thanks for the posts on this topic, it really helped me solve this problem
 
#34 ·
I know it been a long time since you had battery problem, But I need your help, going for the gray and orange wires I need the connector, My Cadiallic dealer said no part like that, help me if you can, Thnaks Greatly jim hanna in greater northwest arkansas 2005 v series 44,000 mile and havcing problems, what about how many push button connectors are holding on the front bumper and big expensive plastic parts on the corners, welcome to GM at it best,
 
#36 ·
I just wanted to chime in and say I had the exact same problem. Battery voltage would fluctuate between 13.9 and 11.x, got random battery not charging messages, red battery light on the dashboard, and when the voltage dropped significantly I got some messages about servicing the stability control system.

My engine mounts are going out and I read a couple posts in this thread and they were exactly right. The pigtial that plugs into the alternator had a break in the orange wire. I spliced a new wire in its place and got everything fixed up. It charges constantly at 14v now! It took about an hour to get to the wire, I had to remove the airbox to get to the connector, and the connector fought pretty hard. It took a pick to lift the piece of the connector that locks it in place so I could pull it out. After this, the fix was pretty simple, but I went the extra mile to make sure it wouldn't happen again. I depinned the connector with a needle and soldered longer leads on the pins, then used some small crimp connectors to reattach it to the harness. I then added some electrical tape and split loom to make sure everything stayed in place and undamaged.

Thanks everyone who posted in this thread!
 
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