Another charging system warning
Thread Starter
Burning Brakes
Joined: Apr 2011
Posts: 770
Likes: 2
From: Alexandria VA
Another charging system warning
Hi all, my car has joined the club. Before you respond, i do not have NKG plugs and the battery is 3 months old. I have auto lite xp5245 that are probably 10k miles old and for the most part the car runs great. Occasionally I'll get a service charging system error while at the track but last week at dominion raceway I would get 2-3 notifications per lap and the volts would drop to 10.5-12. I made it home without incident on the hour drive home and never had a problem starting the car. This weekend I was working on my car (other things) and the volts were back to normal (14ish). I have long tube headers... Does that create extra heat that could damage the alternator or connections to it? Thanks for your help!
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
You need to check the voltage at the alternator to see how much it's putting out, check both hot and cold...If the alternator isn't putting out at least mid to high 13s at hot idle it may be bad....WW
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Last edited by WW7; Aug 1, 2016 at 09:34 PM.
Melting Slicks
Joined: Dec 2013
Posts: 2,232
Likes: 315
From: Bridgewater New Jersey
I remember that while checking my car when I changed the battery, voltage at the alternator post was showing about 14.4 with no load on the system.
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,629
Car idling, and A/C off
Alternator voltage from it back terminal under the rubber boot, to the body of the alternator as the ground point, should be 14.6 volts.
At the battery terminals themselves, should be 14.5 volts.
From the engine fuse block terminal, to the body of the alternator as the ground point, should be 14.5 volts.
Tell me all the readings, and I can tell you the problem and now to fix it.
Alternator voltage from it back terminal under the rubber boot, to the body of the alternator as the ground point, should be 14.6 volts.
At the battery terminals themselves, should be 14.5 volts.
From the engine fuse block terminal, to the body of the alternator as the ground point, should be 14.5 volts.
Tell me all the readings, and I can tell you the problem and now to fix it.
Thread Starter
Burning Brakes
Joined: Apr 2011
Posts: 770
Likes: 2
From: Alexandria VA
Oh wow, didn't get notified of all these responses. I'll definitely check these all out.
Idling with AC on was above 14V on HUD. Haven't dived in yet. I also noticed that when I go to WOT that the voltage drops as my RPMs increase. Normal?
And to the other guy, yes. A lot of people have trouble with the NKG tr55 or whatever. The gap might be wrong and they are meant more for blown cars.
Idling with AC on was above 14V on HUD. Haven't dived in yet. I also noticed that when I go to WOT that the voltage drops as my RPMs increase. Normal?
And to the other guy, yes. A lot of people have trouble with the NKG tr55 or whatever. The gap might be wrong and they are meant more for blown cars.
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Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,629
No, the problem is they don't have the needed resistance to act as RF noise suppressors (why the stock plugs and wires have the higher resistances in the first place).
Hence with the plugs, you get RF noise back through the coils to the ECM, and since the ECM is controlling the output voltage of the alternator as well, The RF feed back noise in the ECM ends up with the ECM clipping the normal 14.6 volts of the alternator, down to much lower voltage isntead.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I posted quite a few times on this issue but it has dropped from recent posts so it isn't popping up in a search. Changing your spark plugs will fix the issue with the charging system. It has to do with the voltage/current read by the PCM which does a sum check. I've seen the fix work so many times yet people resist the advice. I guess it is common to after market plugs.
EDIT: Do a search for 'C6 charging system spark plugs' on google
EDIT: Do a search for 'C6 charging system spark plugs' on google
Last edited by SpinMonster; Aug 10, 2016 at 08:07 PM.
Race Director
Joined: Aug 2005
Posts: 13,592
Likes: 187
From: Hudson WI
NCM Sinkhole Donor
I posted quite a few times on this issue but it has dropped from recent posts so it isn't popping up in a search. Changing your spark plugs will fix the issue with the charging system. It has to do with the voltage/current read by the PCM which does a sum check. I've seen the fix work so many times yet people resist the advice. I guess it is common to after market plugs.
EDIT: Do a search for 'C6 charging system spark plugs' on google
EDIT: Do a search for 'C6 charging system spark plugs' on google
Not saying what he said is right or wrong, just reporting what he told me.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I was talking to the Autolite guys at the drags about that. They say it is problem, of course, they said it wasn't a problem with their plugs because their resistance is consistent. They claim the reason it happens with competitors products is because the system checks the resistance and sets the light off if there is much variability. To quote him "the plugs act a safety check".
Not saying what he said is right or wrong, just reporting what he told me.
Not saying what he said is right or wrong, just reporting what he told me.
I had the issue and plugs always fixed it but as my car was a 19lb boost, I had to use colder heat range plugs so I dealt with it happening every few thousand miles. The first time I swapped them and it jumped up to 14.4v, I thought it was a fluke so I put my TR6's back in and donw to the low 12's it went. I'm a believer.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11