# '06 and newer Chevy HD charging issues



## Zigblazer (Aug 1, 2010)

I'm just checking to see if anyone else is having charging issues with their 2006 and newer Chevy HD pickup while using a plow. I don't have a plow on my '06, that is what I bought the '87 for. But my Dad is having issues.

He bought a 2008 Chevy Reg Cab Long Box 2500HD 6.0L gas pickup new in 2008. It still has less than 10k miles on it. He only uses it to pull a trailer, his boat, and to plow. He special ordered it with the options he wanted, Including the Snow Plow Prep Package. He had a Western Pro Plus 8' plow installed before the first snow fell after he bought it. I think he took delivery in Apr 08 and had the plow installed in Aug 08.

Short story long, his alternator quits charging when he uses the plow. After a few lifts and turns it drops the charging voltage to 12.8V. It is not draining the battery that bad, it simply stops charging at its normal 13.9V. He has taken it to the dealer 6 times now, and to the Western Dealer 2 times. After the first 4 times at the Chevy Dealer when they kept telling him there was nothing wrong, even though they replaced the battery twice, he called me.

I am ASE Master certified and went down to take a look at it. After an hour of checking with no scan tool I figured out the ECM was telling the Alt to stop charging. I found that '06 and newer Chevy HD's use a Alternator that the output is controlled by the ECM. After that he took it back to the dealer and they again told him that there is nothing wrong, it is just the Fuel Saving system going into effect. Problem with that is that once the headlights are turned on it should disable the Fuel Saving system, and putting it into Tow/Haul mode should also disable the Fuel Saving mode. After I had a talk with the dealer, they conceded that it was not the Fuel Saver causing it, and agreed to take another look at it with the regional rep in attendance. They looked at it and the Rep told my dad that it is a design flaw, once the plow drops the voltage the ECM thinks there is a problem and lowers the output voltage to the minimum. He then told him there is nothing they could do and to live with it. Of course my Dad is pissed and is thinking of taking the truck back and telling them to shove it.

My Dad always takes everything in to get serviced, and never accepts any problems. His last truck was 10 years old with less than 50k on it, with absolutely nothing wrong with it. He is a dealers dream customer, always buys new, always does whatever is recommended, and as long as they do it right, he never complains. I called the dealer back and urged them to simply install an Alternator that is not controlled by the ECM to fix the problem for good, but they said they couldn't do it under warranty, and my Dad would have to pay for it, which would void some of his warranty. I would think they would just do it simply to keep a good customer, I mean if they spend $3-400 on a new alternator and keep him as a customer, it would more than come back to them, but what do I know.

Anyway, has anyone else had this problem with their newer Chevys?


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## B&B (Nov 4, 2006)

I'm not a big fan of the new style charging system design but it does generally work. Although not the way we're all used to as you've discovered. 

I've only ever run across this a couple times where it wanted to stay in a low charge state, once was on a truck that wasn't even equipped with a plow. That one turned out to be a defective battery voltage sensor combined with an incorrect calibration. But the ones that were plow equipped the plow installer didn't have the plow power and ground cables connected DIRECTLY to the battery. Moved them to the battery terminals and the system was much happier. Doesn't totally solve the lazy but it allows it to ready battery condition more accurately thus work as intended.


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## Zigblazer (Aug 1, 2010)

His are connected directly to the battery. And once the voltage drops, it doesn't come back up until you shut the truck off, and restart. What pisses me off is that according to the rep GM knows there is a problem with their programming, and they don't care, and won't do anything to fix it. 

I thought adding a second battery and running the plow off from that with smaller cables connecting it to the original battery would make a difference too.


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## vegaman04 (Dec 12, 2007)

So would just installing an 05 or older alternator fix this issue? Anything else have to be done to remedy this, disconnect or disable the ecm control?


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## Zigblazer (Aug 1, 2010)

I know there are 1-wire alternators available, and I'm sure that you could get a non-computer controlled one that fits right in. But the dealer won't do it under warranty (or just to make a customer happy) and my Dad doesn't think he should have to replace the Alternator on an almost new truck, especially when it is GMs fault it isn't working right in the first place.


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## no lead (Dec 10, 2008)

ever wonder why they went out of business and ford didn't?


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## vegaman04 (Dec 12, 2007)

Is that all you ford boys complain about? Yes GM took money, they also paid it ALL back. FORD also borrowed money a few years ago from the market. They all have been hurting.


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## plowking15 (Jan 16, 2010)

I have the plow prep package on my 07 2500HD. It came with double batteries,higher amp alternator and skid plate. Your father's truck should have two batteries if it has the snow prep package. plowking


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## Zigblazer (Aug 1, 2010)

That's what I thought. But I did check, it does have the High Output alt and Plow Prep, but no second battery. It is the 6.0L gas engine, I don't know if that matters, but my truck is the Diesel so it has both batts anyway and I can't compare the two.


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## B&B (Nov 4, 2006)

no lead;1087947 said:


> ever wonder why they went out of business and ford didn't?


 Actually the Fords have been a problem for years. Just getting their PCM controlled system to begin to charge is sometimes a feat in itself. If that's news to you consider yourself lucky. 



plowking15;1088039 said:


> I have the plow prep package on my 07 2500HD. It came with double batteries,higher amp alternator and skid plate. Your father's truck should have two batteries if it has the snow prep package. plowking






Zigblazer;1088055 said:


> That's what I thought. But I did check, it does have the High Output alt and Plow Prep, but no second battery.


Aux battery was a separate option.

Adding a second battery will help slightly but won't solve it. Need to run a completely independent isolated (from the main system) alternator and battery dedicated to the plow. More effort than it's worth since it's still charging...just not as you want it or expect it to.


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## mike1316 (Sep 16, 2007)

Hey there go to the chevy form and ask for b and b help he has helped me with all my proe


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## mike1316 (Sep 16, 2007)

Problem. Sorry about


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## plowguy43 (Jan 2, 2008)

Did you not notice that B&B has been responding to every post in this thread?

I see the OP's problem with all of this but at the same time you can't blame the dealer for not covering an aftermarket altenator under warranty. It sounds like a programming issue that could be solved by new programming. Is there a way to command full charge from the altenator with a scan tool?

For instance- on my truck I was able to command my fog lights to stay on while my high beams are on by using the chrysler scan tool through the vehicle computer. Its just an example, but sometimes there are ways to make the computer do things that weren't intended by the factory.


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## Zigblazer (Aug 1, 2010)

First - I see the reasons the dealer won't do anything, however I also worked at a Med/Heavy truck dealer for 7 years and know what we would have done. We would have fixed the problem ourselves and just ate cost to us simply to keep the customer happy. Our dealership understood that loosing a few thousand now would usually come back in repeat business as well as a happy customer spreading the news that we were a good dealership to work with. I think in school they said a happy customer would tell 2 people about the good experience, but an unhappy customer would tell 20 people about their bad experience. Which makes sense, most people won't talk about a business that did what they expected, but won't stop talking about one that screws them. So I understand that it was not that dealers fault, and they shouldn't have to eat the cost of fixing the problem, but it would have been much better business for them if they would have. They are in a small town and rely on word of mouth. And I'm sure my Father will tell everyone about them not standing behind the new truck they sold him.

As far as GM is concerned, they won't spend the time on reprogramming a fix unless enough people have had the problem. Simple economics. They don't care about loosing a couple customers, it won't hurt their bottom line.

So I was just looking to see if anyone else has had this problem. Or maybe everyone else running a Chevy HD has a 2 battery setup that is just enough better to not have a problem, or his plow is pulling a little more juice than most since it is the Western Pro Plus heavy friggin plow.

I don't know what he has done yet, but I'm sure GM has been getting an earful, or he already has his lawyer involved.


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## JCByrd24 (Oct 19, 2005)

I did not have as bad of a charging problem but my 06 1500 on the stock battery would go low enough to trigger the battery light and and ABS message in the mesage center because the ECM did not react quick enough to keep the voltage up. Upon a recomendation from here last winter ( I believe from B&B) I replaced the stock battery with a better one. I went with a Sears Diehard Platinum, which appears and is rumored to be made by Odyssey (a very highly respected battery manufacturer). It solved my problems as the voltage didn't drop so low before the alternator was told to charge. I believe I also heard the GM batteries aren't great, and I recall the specs (Ah) weren't as good as Diehard. The more AH, the less voltage drop while running the plow motor. Dual batteries would certainly help this without a totally separate alternator, but I'd try the biggest/baddest single you can find anywhere outside of a chevy dealership and highly recommend the Diehard Platinum.


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## Zigblazer (Aug 1, 2010)

I don't know what he's done with it yet. He is fairly stubborn, and may have not done anything that would cost him any money, and waited for GM to cut the bull and fix the problem.

As far as batteries go, GM used to have great batteries, at least they did 20 years ago, and now I think they have fallen flat. Unless DieHard has changed in the last 10 years, they were junk. Interstate used to be great, and I haven't had any experience with them lately. I don't know what batteries are good anymore. They all seem to have changed on me.


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## jimmysnow (Jan 26, 2012)

i have te same low charge problem on my chevy 2500hd 2010....what you do for fix it....my blade kit is the new fisher xls......thanks


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## Zigblazer (Aug 1, 2010)

We did get it fixed this summer. When I got EFI Live for my truck, I bought a tune for his also. With his tune I disabled one of the alternator codes. Then I cut the control wire to the alternator and ran the alternator end to another 5 volt signal from the ECM that would not turn off.

Long story short, his Alternator is no longer controlled by the computer. Anytime the engine is running it gets a full 5 volt command signal to produce full voltage from another source.

So far this winter he has not had a problem. We also haven't had much snow, but I would assume that he would have noticed a problem by now. He found out his wife had cancer the next day, so we haven't talked about it since. He has been fairly busy since then.

I don't remember what the code parameters were, so I don't know if the check engine light would come on without the tune to tell it to ignore the circuit, but it would have set a code from cutting the wire. I can check what the original tune was set for once my garage is warm today, this computer doesn't have the EFI Live program on it, my old one in the garage does.


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## jimmysnow (Jan 26, 2012)

First i whish her good luck in cancer treatement......................but for the truck with always 5 volts what is the output voltage... Because its possible to charge near 15.50 at full duty cycle......the best is near 80% of duty cucle to get 14.70 and do you think with efi live is possible to order a recommand duty cycle at the computer????for the alt... Thanks for your precious help


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## Zigblazer (Aug 1, 2010)

EFI Live only changes ECM or TCM functions. The alternator is controlled by the BCM so it doesn't help.

His wife is doing much better, by the way. Her liver is very slowly improving, but was in complete failure for a while, on the verge of needing dialysis. 

Ok, I can't remember exactly what I did. But it worked, and the output stayed at around 14.7volts. I have been so busy since then. I will have to figure it out again. I see where there could be a problem, but I can't remember what I did to not have the problem.


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## Zigblazer (Aug 1, 2010)

I think what I did was cut the L terminal wire and run the Alt end to another 5-volt signal. The F-terminal was the duty cycle (square wave) output signal from the Alt. I checked the voltages and duty cycles on both terminals while it was running. I found a straight 5 volts on the L and a square wave on the F just like I was expecting. It would drop to 0 on both when the BCM shut if off.

I found this good description;

"The PCM supplies 5 volts through the L circuit to the generator. If the generator becomes inoperative, the PCM can detect the fault through the L circuit and tell the IPC to illuminate the volts telltale lamp.

The PCM monitors the duty cycle of the generator through the F circuit. As the generator load increases, the PCM will adjust the idle speed accordingly. If the IPC does not see any activity from the PCM on the F circuit, the IPC will illuminate the volts telltale lamp."


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## ratherbfishin (Aug 1, 2011)

I am having similar issues(thread started on this forum) with my 2011 2500HD.Same BS from the dealer...it's normal.My rig is obviously under warranty,so my hands are kind of tied.I left the dealer telling the service rep.that if my trck dies in the middle of a storm,I'll be lookin for ya!


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## gbrockway (Feb 24, 2012)

I have the same issue with a 2009 K2500H 6.0 snow plow package.


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## jimmysnow (Jan 26, 2012)

My 2010 is fix now\\\\\\\\\\\\\\\\\\\\\ yessssssssssss ssssssssssssiiiiiiiiirrrrrrrr


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## vegaman04 (Dec 12, 2007)

So what did you do to fix it.


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## gbrockway (Feb 24, 2012)

gbrockway;1456313 said:


> I have the same issue with a 2009 K2500H 6.0 snow plow package.


I ended up buying a new 2012 K1500 with the snow plow prep. I charges fine.


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## Triple L (Nov 1, 2005)

This is not just on the gas trucks... On my 09 diesel everytime your run the plow or dump body the alternator powers down but a few seconds after it comes right back to life... When its cold in the morning it also takes a good 2-5 minutes for the alternator to come to life as well which I always thought was wierd...


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## jimmysnow (Jan 26, 2012)

body control reflash but is not every gm dealer know how to see if the truck need a reflash.....its only to improve your charging system...


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## Triple L (Nov 1, 2005)

jimmysnow;1469053 said:


> body control reflash but is not every gm dealer know how to see if the truck need a reflash.....its only to improve your charging system...


You wouldn't happen to have the service bulletin do you?


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## jimmysnow (Jan 26, 2012)

no service bulleti but can find by the vin number if the truck have reflash to do


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## Zigblazer (Aug 1, 2010)

That's great, that they are finally doing something to fix the problem. I wonder how far back they are updating the BCMs. It's about time.

My dads truck has worked great all winter. They didn't get a lot of snow, but he said charging never dropped once. So he wouldn't need the reflash anyway.


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## ratherbfishin (Aug 1, 2011)

what is a reflash/body control reflash?


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## jimmysnow (Jan 26, 2012)

Reflash ...is put a new programation in the body control computer my truck is 2010 ...


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## Greenmtboy (Jan 22, 2011)

Same problem here. 2011 1 ton 6.0, plow prep. package, came with one battery and it doesn't not charge well while plowing. Dealer said the same "everything checks out fine". I put a second battery in it and did not change anything. Would be nice to get this straightened out. 
For those of you that have a 6.0 that came with factory dual batteries (not sure if this applies to 2010 an earlier or not) may want to check with your dealer, but I believe that second battery is an RV option. That meaning that it is set up with an isolator and goes to the trailer plug to run your camper and would have no benefit for running a plow, sander, etc. unless they are hooked up to that second battery. I could be completely wrong, and if I am please feel free to share your knowledge.


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## ratherbfishin (Aug 1, 2011)

Some how we all have to get to the bottom of this issue/potential issue.Is there any GM reps on this site,or anybody who knows one?This is annoying and always gives me a bad feeling plowing.I find it very hard to see it as normal as the dealer calls it!


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## jimmysnow (Jan 26, 2012)

i put dual battery not with the factory r.v systemsend me a private message with your vin number and maybe i can tell you if some gm update is disponible for your truck


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