Service Charging System
Team Owner
Joined: Dec 2002
Posts: 32,074
Likes: 296
From: San Francisco CA
What I'm seeing is when it first starts up, the analog gauge will sweep all the way up which is normal, then come back down to the lower voltage reading and instantly pop up to 13-14vdc. What it was doing is that sometimes it wouldn't pop back up till I touched the gas. Since I replaced the battery, it hasn't stayed down since, so far. I understand that the pcm or ecu is controlling the amount of charge from the alternator/generator which sort of points to either the alternator or the pcm being the cause. If my issue comes back, I have to wonder if either of those items are covered by the 5yr/100K warranty for the power train?
Melting Slicks
Joined: Jun 2002
Posts: 2,168
Likes: 16
From: Phoenix AZ
vetracer,
I wasn't necessarily suggesting that it might be your horn.
What I meant was that perhaps there is some other electrical item which has a direct (or near-direct) short. I realize this would be a real pain to trouble-shoot. But you might have to look at all aspects electrical... lights, heater fan, etc., etc.
In any event, I do wish you Good Luck.
I wasn't necessarily suggesting that it might be your horn.
What I meant was that perhaps there is some other electrical item which has a direct (or near-direct) short. I realize this would be a real pain to trouble-shoot. But you might have to look at all aspects electrical... lights, heater fan, etc., etc.
In any event, I do wish you Good Luck.
I spoke to my tuner who says that he has had 3 cars in the last 3 monts with the same problem. He is going to turn off the code. We're wondering if it is heat related, as the A/C is usually blowing full blast and the components themselves are taking a pretty good heat bath...
Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
I'm seeing 14.3 to 14.4 normal. When its running down the freeway, always about 14.1 - 14.3. Now if I get stuck in traffic, it slowly starts dropping down but not usually below 13.4 -.5
As its heating up out here, I'll know more if its heat related. I work the 2nd shift so middle of the day heat driving in and cool at night coming home. We're not full blast summer here yet, but its coming. During the hot times, we can see upwards 105 to 118 on the roads. I saw 118 ambient here at my house on a single day last year. Original battery in the garage is showing 13.1 static still...fyi only
As its heating up out here, I'll know more if its heat related. I work the 2nd shift so middle of the day heat driving in and cool at night coming home. We're not full blast summer here yet, but its coming. During the hot times, we can see upwards 105 to 118 on the roads. I saw 118 ambient here at my house on a single day last year. Original battery in the garage is showing 13.1 static still...fyi only
Team Owner
Joined: Dec 2002
Posts: 32,074
Likes: 296
From: San Francisco CA
I'm seeing 14.3 to 14.4 normal. When its running down the freeway, always about 14.1 - 14.3. Now if I get stuck in traffic, it slowly starts dropping down but not usually below 13.4 -.5
As its heating up out here, I'll know more if its heat related. I work the 2nd shift so middle of the day heat driving in and cool at night coming home. We're not full blast summer here yet, but its coming. During the hot times, we can see upwards 105 to 118 on the roads. I saw 118 ambient here at my house on a single day last year. Original battery in the garage is showing 13.1 static still...fyi only
As its heating up out here, I'll know more if its heat related. I work the 2nd shift so middle of the day heat driving in and cool at night coming home. We're not full blast summer here yet, but its coming. During the hot times, we can see upwards 105 to 118 on the roads. I saw 118 ambient here at my house on a single day last year. Original battery in the garage is showing 13.1 static still...fyi only
That's way too hot for me...very unhealthy better get that air cond. on recirculate fast.
Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Yeah, I agree...anyway, it happened again today as I was putting gas in it. Engine hot, outside temp hot... Start it up, volts were 12.2, HVAC running full blast, engine fans of course running at warp speed...not enough juice to keep up a charge unless I raise the throttle. I'm guessing the regulator portion of the alternator generator has lost it. Back in the old days, one of six diodes would probably be bad or a bad winding...who knows these days with computer controlled alternators. I'm going to stop by a alternator repair place tomorrow morning and see what they have to say.
Team Owner
Joined: Dec 2002
Posts: 32,074
Likes: 296
From: San Francisco CA
Yeah, I agree...anyway, it happened again today as I was putting gas in it. Engine hot, outside temp hot... Start it up, volts were 12.2, HVAC running full blast, engine fans of course running at warp speed...not enough juice to keep up a charge unless I raise the throttle. I'm guessing the regulator portion of the alternator generator has lost it. Back in the old days, one of six diodes would probably be bad or a bad winding...who knows these days with computer controlled alternators. I'm going to stop by a alternator repair place tomorrow morning and see what they have to say.
Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
It appears the alternator has lack of sufficient current issues as well as fluctuating voltage issues. They ordered one for me which I should be able to pick up tomorrow morning. Once I have it, I'll replace it and see what happens.
Burning Brakes
Joined: Dec 2004
Posts: 793
Likes: 0
From: Wheaton Illinois
I experienced exactly this same thing for the first time last week. I took the car to my dealer, a very experienced Vette dealer I might add, and the tech told me he could not find any cause for this. He checked the battery, alternator etc., and everything was performing as it should. After another week of driving, the warning message has not returned. The tech told me to which it, and if it comes back, his thought is that it may be a computer glitch.
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Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Hey WingRider, Mine works fine at night or whenever cooler. When this happens as it was today again, its when there is a full electrical demand on the system. It was 99 degrees outside, HVAC comes on full blast and of course the radiator fans are screaming too. Battery voltage will not maintain and even erratic on the DIC, but slowly losing voltage when idling in these conditions. Bring the idle up to say 1500 rpm, it starts to recharge. I'm thinking one of the 8 diodes inside is shorting out when it heats up therefore sapping the current as the voltage drops off pretty fast when idling. Anyway, you might want to try that...full electrical load when starting up and see if you are maintaining or losing. If losing and you are under warranty, force the dealer to look at it again with the additional information. The new alternator is $501 from them. I got a rebuilt from a Alternator shop that's been in bubsiness for 40 years. Not sure its correct though as it is not an exact match but close. I'll put it in tomorrow morning when the car has cooled off (I'm at work 60 miles away with it right now through tonight) and see what happens. I'll certainly load it down all the way and heat it up along with tomorrow's heat might be breaking the 100's.
Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
I need someone to do me a favor please. Whomever, please check your battery analog and digital gauges after its been heated up full, driven, hvac running and so on. When you restart it, please tell me what the analog and digital shows? Is it running on the low-voltage side of things? This means under a full electrical load... I replaced the alternator on mine this morning after having already replaced the battery and it all appears to still be doing the same as before, low voltage when at idle, full electrical load on, hot and so on. It doesn't start charging till the rpm is raised. Even after a full hour of driving on a freeway, battery at a full charge, I come down to idle and the battery starts losing it immediately.
Heel & Toe
Joined: May 2005
Posts: 23
Likes: 0
From: Manama, Bahrain
I need someone to do me a favor please. Whomever, please check your battery analog and digital gauges after its been heated up full, driven, hvac running and so on. When you restart it, please tell me what the analog and digital shows? Is it running on the low-voltage side of things? This means under a full electrical load... I replaced the alternator on mine this morning after having already replaced the battery and it all appears to still be doing the same as before, low voltage when at idle, full electrical load on, hot and so on. It doesn't start charging till the rpm is raised. Even after a full hour of driving on a freeway, battery at a full charge, I come down to idle and the battery starts losing it immediately.
Before full load: 13.8V
After full load: 12-11.8V
I don’t know if this is normal or not, but same as you it starts charging as the rpm increases.
Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Thank You "MHD" for your effort. Its starting to look like the alternator doesn't put out enough current at idle to maintain the battery but I sure don't remember this happening before and I would think I would have noticed it. Appreciate your trouble for me. 
Burning Brakes
Joined: Dec 2004
Posts: 793
Likes: 0
From: Wheaton Illinois
The problem seems to have vanished. After ten days of daily driving, the warning has not returned. As to the full load situation, I have never gone to negative on the voltage, regardless of load, so I am afraid I cannot be of any help. Maybe my tech was right, and it is/was just a computer hic up.
Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Update today 7-13-09, The original alternator was verified bad by a place that I trust. The rebuilt that I put into it, apparently has the same indicated problems that the original had, however it wasn't removed and tested, only in-car tests and my seeing the same issues. Tomorrow morning, its getting a brand new GM alternator. I don't know yet if there are other problems still yet such as wiring or the PCM controlling it, but will find out in the morning.
Burning Brakes
Joined: Dec 2004
Posts: 793
Likes: 0
From: Wheaton Illinois
Just like MHD today. 85 degrees outside, full load, stuck at idle on expressway. Temp went to 228, and voltage dropped to 11.8. As soon as I got back to speed, everything tuned back to normal. (tem[ of 202 and 13.8 to 14.2 on charge.) So, I guess it is just a heat thing.
2006 A6.
2006 A6.
Melting Slicks
Joined: Jun 2002
Posts: 2,168
Likes: 16
From: Phoenix AZ
I've put mine through a lot of heat, load and hot restarts lately, and still no problems with the charging system. As far as programming out the chime and message, all I can say is silence from the DIC really is golden...
Thread Starter
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
You know what's weird with this...I drove it today all over, totally hot with no problems. Got back to my small one-car garage and parked it for an hour before going to work. I had no problems with the charging. I go back out there to leave for work and sure enough, low voltage on the DIC and analog.
I was able to get under it this morning enough to see that the major electrical interconnect for the car is at the starter solenoid. The ground cable is attached to the engine block right there close to it as well. I see several power feeds coming too and off of the main solenoid power connection. Tomorrow morning when its cooled off again, I'll remove the cat then access those cables and see if anything needs re-crimping, lose or whatever. I suspect that the heat from the cat is causing this issue but truly, I'm not sure at this point.
I was able to get under it this morning enough to see that the major electrical interconnect for the car is at the starter solenoid. The ground cable is attached to the engine block right there close to it as well. I see several power feeds coming too and off of the main solenoid power connection. Tomorrow morning when its cooled off again, I'll remove the cat then access those cables and see if anything needs re-crimping, lose or whatever. I suspect that the heat from the cat is causing this issue but truly, I'm not sure at this point.
