I need some help troubleshooting this problem. Here is what happened:

(Car is a 2005 coupe with a supercharged LS2. Stock electrical system, no mods to any electronics other than a dyno tune.)

The large red wire to my alternator fell against the header while I was driving. It burned thru the insulation and shorted out. The car went a little crazy with flickering lights, and bells, then died.

I found the wire and repaired it. I cut out the burnt section and soldered the two ends togeather. The Boost-A-Pump also blew, so I removed it and wired the fuel pump back up as factory. I went through all of my fuses and can not find any that are blown.

The car now starts up and drives just fine, except I get a "Service Charging System" message on the DIC. I removed the alternator and took it to the local O'Riely's Auto Parts for a free bench test. The kid there said it all looked good. I put it back in the car and still have the message. So I drove the car to O'Riely's to have them check the charging system with their handheld diag box. It showed that the regulator was putting out a low reading.

I then pulled the alternator back out and took it to a reputable rebuild shop accross town. The guy just called me and said it checks out just fine...no problem with the alternator.

So now where do I turn?? The alternator checks good, and all of the fuses apear to be just fine.

Note: The voltage guage read almost 12 volts at the start of a 5 mile round trip (10 min). By the end of the trip it was at 11 volts. Not sure, but I would think if it was running strickly on the battery, I would see it drop more than that.

 

Some messages take several ignition cycles before they are reset. This may be the issue... not 100% sure.
What condition is the battery in... ? Seems low on voltage

 

Battery is an original Delco. I put a charger on it for an hour while I was repairing the cable. Could be a little low/weak, but it has not given me any problems in the past.

I could put the charger on it overnight and see if anything changes.

 

I tend to think it ruined your alternator even though it passes their simple test. Before replacing it though, check all the cable connections at the battery as well as the starter. Static voltage across the battery should be 12.5 when the car isn't running and the battery is disconnected. If its below that, the car isn't going to work correctly. Now to check the alternator yourself or specifically the voltage regulation...the old school method should still work. With a meter connected across the battery, start the car. You should see 13.8 to 14.3 volts... if not, alternator is gone or the connections to the battery are having problems. If it is low but coming up, cool, but put a load on it such as turning on the lights. The voltage should drop off very briefly and recover within a second or so. If it doesn't, regulator is bad which is part of the alternator. Now on these cars, assuming its similar to the C-5's, the PCM/ECM controls the charging of the alternator based upon its measured load/need. Its possible that you toasted it...this means a trip to the dealer and lots of $. Will hope for you that its only the alternator.

 

If you car runs fine then I wouldn't worry about it.

I have the same problem. I have a 06 A6 with a Vortech supercharger. I would have the "Check charging service" display for a few seconds, then it would disappear. It would happen every now and then. Took the car to a dealer to check it out and they said that the problem was because I am not running the stock spark plug (had to change to a colder plug due to the supercharger). So far no problems except the message still comes on once in a while.

 

GREAT information!! Makes sence and I should be able to run the tests tonight.

So the PCM/ECM controls the regulator? If the test fails on the battery check under load, then I have either a bad regulator in the alternator, or a bad PCM/ECM control function, correct? Is there any way to isolate between these two??

 

Ummm.... my problem might be a little different. My message stays on constantly, and my voltage reading is pretty low. I have had the supercharger installed for a few months now and I have never had this message before. Not that I would discount your advice, but I want to make sure that there truely is no problem first. Thanks!

 

The battery should have about 12.6 volts just sitting and 14 volts when running, indicating the charging system is working. If you have 11 volts after a short run something is wrong, possible the internal voltage regulator.Good Luck , John

 

Since you say you have the original Delco Battery, it potentially could be 4 1/2 years old. Whatever your problem turns out to be (and it may just be a bad battery) pcm/ecm module, alternator or whatever.....I would replace the battery first and go from there. Eliminate the easy stuff first.

 

 

Good idea!!

I just got home from work and it is 10PM here. I will do some tests tomorrow after work and post up what I find. Thanks for all of the advice!!

 

The Beast is FIXED!!!

Thanks Impulsive for the skizmo!! And thanks to DCLaflure for making me re-think my electrical connection!!

Problem ended up being the fusable link within the Alternator heavy power cable. The link is located right down by the starter. It's good to know that it did its job and opened when the 12V 145 amp cable shorted against the header!! It was a bitch to figure out at first becaust the link melted internally within its insulation. I had high resistance from the Alt to the pos battery cable. And it would sometimes open when I moved any wires even slightly. The Skizmo put me right on it!! Thanks again Chris!

Since the surperchargers Boost-A-Pump was getting its voltage directly from the Alt output terminal, it is not fried at all!! It was actually not getting any power because of the fusable link. SWEET!!

So the only think I had to do was get a new Alt cable. GM wants $96 for it, and it will take a week to get here!! So I went to the junkyard and got a late model truck Alt cable with the fusable link built in. I then took it to Spectro Wire in Moore and they put heavy duty crimped/soldered ends on it for me that matched my factory connections. All togeather the total repair cost was$6.42!!! Hell YEAH!!

Much better than shotgunning the alternator + battery + ECM + ??? Those three items along would cost $800+!!

Thanks again to all for the advice and pointers!!

 

Now you've taught me something too... I didn't know there was a fusible link down there. Good info.