Charley Hoyt

I have been intermittently getting a “Charging System Fault” message on my DIC. I brought the car into the dealer a couple of times but they said that they could not duplicate because it was intermittent (despite a code being set). Over time (a year or so) the problem has gotten worse. The message now appears at least twice every time I drive the car. I brought it back to the dealer and they said that they:
1) Found code P1638 in history
2) Tested Charging system and battery
3) Performed bulletin / calibration search
4) Tested generator to PCM wires
5) Inspected PCM connection
6) Inspected Misc. grounds and feeds as suggested by technical support

But they still can’t figure out what is causing the “ Charging System Fault” message to appear.

Any help with this would be greatly appreciated.

By the way this is not intended to be a dealer bashing thread….I just want to fix the problem.

Charley Hoyt

Any help out there???

HOTSOSS

can't really help, but mine seem to do that once, I noticed that after starting the car, the voltmeter sat at 12 volts, which means nothing is charging, and I got a flash on the DIC something about the charging system. But later after driving it, the voltmeter went to 13+ volts and haven't had a problem since. I figured that the regulator part of the alternator must have stuck for a few minutes, or the battery was going bad, but its been 5 months since and everything is normal. Hope you figure it out, cause you never know when its going out for good and your stuck.

SAXN8R

This used to happen on my '01. It has only happened once in my '02. The message is generated from an over or under voltage condition. I am not sure what the parameters are. There is a range, lets say 11.5 to 13.5 that the PCM thinks is acceptable voltage. When it gets out of the range, it trips the message. If it is in history, it is not currently happening. If it is current, than you have a problem. I think (this is just my best educated guess) that the reason you are getting this problem is because during start your battery and therefore electrical (charge system) is momentarily falling below the specified parameter for allowable voltage. 11.5 in my example. This trips the message. You may or may not be able to make the message go away by getting a new battery. I am pretty sure that batteries are not perfect. What I mean by that is that one battery may at full charge hold 12.3 volts, another might be at 12.1. Yours may just not be able to maintain the minimum voltage parameter during start because of the high draw from the starter. I would be willing to bet that the message goes away in warmer weather.

My conclusion is: Don't worry about it. If your system is charging and the message stays in history you are good. Don't get a new battery to make it go away. It may or may not work. It is just a "C5" thing that some of us have to live with. The only thing that would probably fix your problem would be if GM would modify the software to make the acceptable battery voltage parameters a little bit more lenient.

Take care,

HOTSOSS

And I guess its possible that your battery is starting to go bad. May want to have it "Load Tested". Since I have a two boats with trolling motors, I bought a load tester from NAPA just to test the 9 batteries I have between cars and boats. It's about $40 but well worth it and easy to use. Good luck.

Kenny94945

Hello,
I recall a thread about checking the tightness of the wires at the starter.
Good luck; let us know if you find they need tightening.

SoCal C5

Have you noticed the battery voltage when the message occurs. A low voltage could be causd by a number of things but a high voltage can really only be the alternator.

1999 White C5 Coupe

Charley Hoyt,

You did not post the year of your C5, but I'll provide information from my 1999 C5 coupe with the same/similar problem.

I repeatedly received "charge system fault" messages - Mr. Goodwrench was stumped despite several visits. He called Chevrolet Technical Assistance and was told to check several ground locations on and near the starter. He found several ground strap nuts loose and the studs were corroded. He cleaned the locations with a wire brush and then reattached/tightened the nuts. After this was done, I did not receive any more messages.

I hope this helps - good luck.

Charley Hoyt

Yes, My voltage is fine (between 13 and 14 volts) when the message goes on. The dealer did a load test on the battery (which is an optima red top). The checked the cars electrical system and found that it is making good power. They checked the grounds and added another ground strap per a service instruction......and I still have the problem????

ROCKnROLL

i'm a big believer in second opinions. you got some good advice and suggestions from the members that replied to your thread. i would take it to another dealer or shop and have it checked out again. nobody's perfect. it's just possible something is being overlooked.
let us know how it comes out.

Ketch2631

My 99 flashes the message about once a month. I took it to the dealer and they couldn't find anything wrong with it even though the code was in the history. It has flashed in 100+ weather and 20+ weather. I wouldn't worry about it. I think it is just a C5 quirk we have to live with.


[Modified by Ketch2631, 1:11 PM 12/13/2002]