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Discussion Starter #1
Started last Friday, was fine over the weekend, but last night, went crazy again.

Now we are afraid to take this thing on any sizable trip, if the battery goes dead, we would be stranded, very well cared for and only 40K miles on it.

Here is the circuit diagram:

View attachment 168562

The thing is, without having access to the source code of that ECU controlling the alternator, I don't know what to do with this problem. Next to impossible to go conventional without a real ignition switch!

So what should we do with this well cared for vehicle, dump it? There are zero trouble codes, have a darn good scanner, not even any in history. Something is indubitably switching off that alternator, and without this, that battery would go dead, and if on the freeway, would not be any different than those failed ignition switches and could lead to a severe accident. Not so much with me, but my precious wife drives this thing.

This is your problem, are you going to fix it? Do I go to court, or just dump this darn thing. Very frustrated right now, no excuse for this.
 

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Nick,
I wish I could give you a definitive answer but after watching my own 2012 readout your seeing the same thing as I relative to output.

I haven't a clue what the parameters are that were chosen for the variable output but evidently they are within the battery's requirements.
I don't recall anyone on the forum requiring a alternator or module replacement for a charging problem.

Sometimes I wish the display wasn't available.....ignorance is bliss, heh heh.

Odds are, you are seeing the same variables we all are and there is no cause for concern, IMO.

I have only picked up on one consistancy......the display voltage is generally lower as ambient temperature drops....but I haven't chosen to cause myself any brain damage by speculating......I see the same variable with my truck which has a formal voltmeter.

IMO...change to a mileage readout and don't frett over it.

Rob
 

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Discussion Starter #3
When this occurs, the radio display also flashes on and off, even with the radio off, this is noticeable.

Should also do a battery capacity check, suppose to be a 60 amp-hour battery, if undercharged for periods, could only be a 10 amp-hour battery.

Could also pull the alternator, put it on my test bench and learn the parameters and check the temperature coefficients. From the circuit diagram, you can see where the ECU has full control over the alternator, very familiar with the regulator terminal nomenclature, but not sure whats on the other end.

My name is on the inventor of a now long expired improved voltage regulator design that proved to be very reliable for the CS series. But all that got me was to keep my job while other engineers were laid off. Pinouts are the same on this new one.

And I have a darn good reason to feel concerned about this. And this should be GM's problem to resolve.
 

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Ah.....

The radio thing.....should've mentioned that.

I remember when you modified the clamp on your negative battery terminal........turns out the actual failure is where the cable enters the clamp and is then crimped......some not hard enough and resistance begins to increase within.
Since the voltage readout is just the measurement at the hall ring surrounding the cable........gotta wonder if the cable is going away at the crimp.

Thinking out loud...but may be helpful to get that thing changed.

Rob
 

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You could have a bad battery do all of this. If you have bad cell the alternator may think the battery needs power then it doesn't and your see a drop in voltage. I would have some run a test on the battery. Just testing with a volt meter is not going to show you anything unless you are testing while the engine is starting. It shouldn't drop much voltage. If it does the battery is your problem. Places like batteries plus can test this by causing a load on the battery. They showed me this with my seadoo battery.
 

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Nick,

Have you had GM change the battery cable yet? Also, as we all know a lot of the OEM batteries are crap - just ask JD Powers. Batteries are the number one replacement item in the first three years of ownership across all car brands.
 

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Discussion Starter #7
I can't believe this, thanks for the super simple basic suggestions. Battery voltage is good.

Between the negative battery terminal and the clamp around it, I am getting a voltage drop of 0.005 volts.

But between the clamp on the negative battery and the other end of the terminal that is grounded, not the ground, but the nice clean terminal itself, I am getting a voltage drop of 2.159 volts!!!!! Dropping that much voltage over this very short cable!!!!

The result of this, is that between the positive battery and the vehicle ground, with that extra 2 volt drop in the cable, the charging voltage is jumping up to over 15.5 V fooling the ECU the battery is overcharging, when it is not.

Going to my new dealer to get a new negative cable, the problem is within the cable and the negative battery clamp itself. Not the connection between the clamp and the battery terminal. And not between the cable and the grounding terminal. And not between that grounding terminal and the vehicle ground. One spot that I cannot repair.

I could cut that negative clamp off and solder on a new clamp, but won't look as neat. Let you know what happens. Making sense now, and over voltage of 15.5 volts will cut off the alternator if they are still using my design.
 

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Started last Friday, was fine over the weekend, but last night, went crazy again.
Now we are afraid to take this thing on any sizable trip, if the battery goes dead, we would be stranded, very well cared for and only 40K miles on it.
Here is the circuit diagram:
View attachment 168562
The thing is, without having access to the source code of that ECU controlling the alternator, I don't know what to do with this problem. Next to impossible to go conventional without a real ignition switch!
So what should we do with this well cared for vehicle, dump it? There are zero trouble codes, have a darn good scanner, not even any in history. Something is indubitably switching off that alternator, and without this, that battery would go dead, and if on the freeway, would not be any different than those failed ignition switches and could lead to a severe accident. Not so much with me, but my precious wife drives this thing.
This is your problem, are you going to fix it? Do I go to court, or just dump this darn thing. Very frustrated right now, no excuse for this.


NickD I noticed that you are having similar problems that I'm having with my 2015 Cruze diesel, first stone dead battery with 200 mi new after leaving it sit for a week (nothing left on). Since then I've watched voltage on DIC display and it does vary all over the place (12.0 to 15V). Note that 12.8V or less for a battery with the engine running with accessories on is a discharge state. You reference a wiring diagram, is that for the gas only? I do not see that hall effect sensor on the neg cable in the schematic on my diesel cable, do you have that device on your neg battery cable?
 

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The voltage does vary all the time. If you're having trouble with the electronics in the car and random no-start conditions, have the battery cable changed, as many have suggested. It is a known issue. The ACD batteries also have a habit of losing a cell or two and going flat overnight. They'll hold a charge until the next time the car sits for any period of time.
 

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Discussion Starter #10
Here is the new battery cable I received from my good Chevy dealer under the recall. We tease a lot, said I would like to install it myself, his reply, I shouldn't let you do this, you are way over too qualified. Just replied, I can also be stupid. Wanted to hook up my 12V DC power supply so I wouldn't lose anything. Even got to keep my old cable.

View attachment 168594

After installing it, ran the same exact test and instead of dropping 2.1V across the old cable now dropping 0.0047V. Before letting the engine idle with minimum alternator load, battery voltage after removing the surface charge was, 12.56 volt. Now at 75*F same test, 12.9 volts that is exactly where it should be at. So my my battery before was undercharged. At idle, charging voltage is at 14.72 volts that is exactly where it should be at.

Feel like an idiot for not checking the basics, but tend to do this at times. Dealer just called to make sure I didn't have any problems installing the new cable due to that fuse/relay box small cable that attaches to the negative battery clamp, because he said they had to ream some out. Just said, fit exactly. We also had a rather long talk on the basics as to why this could happen.

Only have the shop manual for the gas, actually alldata.com isn't too bad, I think the diesel is there, but would have to check, if you can find a coupon on the internet, cost 12 bucks for a two year subscription, this is where I copied that circuit from.

Also heard a rattle coming from my 1.4L engine, after some checks, is that Ecotec cover, have to put some tape around those clips.
 

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The result of this, is that between the positive battery and the vehicle ground, with that extra 2 volt drop in the cable, the charging voltage is jumping up to over 15.5 V fooling the ECU the battery is overcharging, when it is not.
Since the DIC is showing low voltage, I think the ECU is seeing the low voltage and commanding "full power" from the alternator - but even at full power, the voltage drop is enough to cause the low readings and the undercharged battery.

At least with my cable, the ECU get's it's ground from the battery clamp itself (the small wire bolted to the battery clamp). So the ECU will see the "dropped" voltage, not the voltage the rest of the car sees.
 

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Since the voltage readout is just the measurement at the hall ring surrounding the cable........
Did someone slip you some decaf this morning? :grin:
 

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Discussion Starter #13
Since the DIC is showing low voltage, I think the ECU is seeing the low voltage and commanding "full power" from the alternator - but even at full power, the voltage drop is enough to cause the low readings and the undercharged battery.

At least with my cable, the ECU get's it's ground from the battery clamp itself (the small wire bolted to the battery clamp). So the ECU will see the "dropped" voltage, not the voltage the rest of the car sees.
Don't want to contradict, but measured the alternator output voltage to the engine block, and this is the voltage that was going crazy. When it jumped to over 15.5V alternator would shut down, and read the battery voltage at about 12.56 V.
 

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Don't want to contradict, but measured the alternator output voltage to the engine block, and this is the voltage that was going crazy. When it jumped to over 15.5V alternator would shut down, and read the battery voltage at about 12.56 V.
Not a contradiction, just more data. Odd that things would shutdown and not leave a code somewhere.

I still think the DIC was reading true battery voltage and not system voltage which is why the system voltage went high.
 

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Discussion Starter #15
More data, now that I think about it, problem was worse at night and even worse in colder weather, or even with the radio on. That high cable resistance is linear, and the greater the load on the alternator, the worse the problem.

With this knowledge, drove 14 miles north to a good dealer for the new cable, very nice people up there in a very small town. Left everything off and the voltage on the DIC held stable. Colder weather at night, the head lamps were on plus the blower motor, along with the radio.

If you have this problem, watch your alternator loads.
 

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Okay last night with the head lamps, blower on full, and the radio on, voltage remained steady at 14.7 volts.

Couldn't resist removing the old cable from the clamp, bare copper wire next to brass, stripped about a 1/4" with about an 1/8th inch perpendicular knife edge crimp making contact to that bare copper wire. If they only dipped the end of that wire in a solder pot first, would not be a problem to prevent that copper from turning brown. Or used plated stranded wire.

Copper oxide is an excellent insulator, ever hear of a copper oxide rectifier? Was used for many years before solid state was invented. I still can solder that cable to the clamp, may do this because the new one looks the same way. Should also check the positive battery clamp.

Shop manager wanted to look at my battery, said most he gets in our green, wow, looks brand new, that is because on day one coated everything with dielectric grease to retard corrosion.

First rule in electrical is to never use dissimilar metals because of electrolysis causes corrosion, this rule is broken a million times. And you wonder why we have problems. Bean counters at work and in charge.
 

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So what kind of crimp was this? Single point, like a cheap auto store crimper? Not 4 point like our good old expensive DB-25 pin crimper?
 

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So what kind of crimp was this? Single point, like a cheap auto store crimper? Not 4 point like our good old expensive DB-25 pin crimper?

Cheap, if brains were used, the crimp would be at least three times as long as the diameter of the wire, an old rule of thumb.

In taking a closer look at the negative battery cable, wonder if the engineer that drew the specification sheet knew that at least of the last 90 years, the positive battery post is 50 mils larger than the negative battery post,

This was done intentionally so the polarity could be reversed, course wouldn't work if some guy tried to bang on a negative clamp unto a positive terminal with a hammer and wonder why the positive clamp was so loose. Post batteries are new to GM, been using side terminal batteries for years. So either the engineer didn't know this or the vendors could not read. The clamp they were using for the negative post would fit just nicely on the positive post. A simple error like this cost GM millions.

Dipping the end of the cable in a solder pot, would also have saved a lot of grief and expense. China could have forced six year old kids to do this at practically no cost, if it was specified.

Never counted the electrical connectors in the Cruze, has to be well over 200, wonder if any more have simple problems.
 

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Discussion Starter #19
Really having nice November weather, in the high 60's, been monitoring my voltage the last few days. And confused about these modes the manual tries to explain. Regardless of night or day, or how many loads I turn on or off, voltage is showing a constant 14.7 volts, and this is exactly where it should be.
 

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Really having nice November weather, in the high 60's, been monitoring my voltage the last few days. And confused about these modes the manual tries to explain. Regardless of night or day, or how many loads I turn on or off, voltage is showing a constant 14.7 volts, and this is exactly where it should be.
I got 13.8 right now (headlights and fogs on, blower off)...just kidding it went to 14.0.......14.2......14.0......14.3. (Fluctuates a lot). I see 14.7 a lot too. Usually though, it's at 13.8. I used to get 12.8 all the time but I think my battery is getting weak.


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