the sarge

I have gotten this message twice now. I've been observing the voltage reading and I don't see anything abnormal but not sure where to go with it. I haven't done anything to the car since I bought it in June but it does have aftermarket audio with 2 amps. I believe the alternator was replaced by the previous owner not that long ago and the battery is about 2 years old. Any advice?

ssrallyred

I have had it show up twice for maybe 2 seconds on start up but went right away. And I also just bought my Z well, Memorial day weekend but basically in June. But that was right after I bought it and never again since. Mine only had 22K on it when I got it and was a garage queen so I was thinking the battery might have just had a low charge as I have not seen it since June.

the sarge

Yeah I don't get it. It shows up then disappears and no check engine light or anything. Will this throw a code I can pull?

sunchaser73

As far as I can tell, the only DTC that could set under this condition is P1637, which is for the Generator L Terminal Circuit. However, I have not personally experienced this code being set. I've had the "CHARGE SYSTEM FAULT" once or twice in the last 5 years. The first time it occurred, I performed the applicable checks from the service manual, and everything checked out ok.

My advice: either perform the load check(s) called out in the manual or have your alternator tested at AutoZone (or somewhere like that). If everything is ok, I wouldn't worry too much about it until a DTC is set in conjunction with that message.

the sarge

Much appreciated I will get the alternator tested. I don't want to be stuck somewhere.

zillionaire2

I've been getting this message recently myself. After searching through the forum I went ahead and checked my ignition contacts. Great post Bill, thanks. My contacts were scorched just as badly as your pictures. Problem is, it didn't fix the problem.
I am still experiencing fluctuating voltage levels after driving 15-20 miles. I've had the alternator checked and they assure me it's putting out the required numbers as well as the diode being okay.
Not only do I get the code but I'm also experiencing stutter and occasionally the engine will die. No problem to restart but very disconcerting.
Is there something else to check or should I just go ahead and consider the alternator bad and change it out? BTW the battery is only a couple weeks old.

Sorry, I've got a 2002 base model C5 with no mods at all.

aobrien14

Zillionaire2 said:

I just put a post up entitled "98 miss" describing EXACTLY the same issue you are having, except, mine hasn't yet stalled, but it sure tries to. I replaced my alternator, but the voltage output is still pretty variable...mechanics thinking something vacuum related, but I now wonder if it isn't something related to the charging system...

Bill Curlee

Seeing Charge System Fault message at initial start up really isnt a big deal and as long as it goes away within a few seconds after start up.
I would much worry about it. What concerns me is; What and how are you checking battery voltage?????

If your are using the Dash Volt meter or the DIC digital volt meter,,, YOU ARE NOT seeing true battery voltage! Both of those meters shows the voltage that is being supplied to anything that the IGNITION SWITCH turns ON when you turn the key to RUN, ACC or Start

Measure the battery voltage DIRECTLY from the battery terminals.

If you want to make sure that your alternator is properly charging the battery, measure the large BATT terminal on the back of the alternator to chassis ground. It should be exactly the same as the POSITIVE battery terminal to chassis ground. IF,,,,,,,,,,,,, there is a difference between the two, you could have a poor connection at the starter solenoid where the wires connect:












This LUG on the frame next to the battery is your CHASSIS Ground lug... It is very important that it is properly grounded and the connection is clean and tight!!

Bill Curlee

Here is why the IGNITION SWITCH voltage output can be different than measuring battery voltage directly on the battery:

IGNITION SWITCH CONTACTS burnt!





You can repair/rebuild that switch:

- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html

Down

Bit of a bump from the dead but I'm dealing with a Charging System Fault error and I'm getting the P1637 error. Sorry for the very novice questions here but:
1. Just to make sure, the BATT terminal you speak of is the BATT connection in this pic, right?

2. To test this, would I need to pierce the protective cover of the plugin to this terminal?

Bill Curlee

Auhhhhhh,,,,,,, You know thats NOT a C5 Alternator,,, CORRECT??????????????????

NO,, The black rubber boot pops off the back and the terminal is easily accessed and measured

Down

Yes, I realize that, lol. I was just lazy and grabbed the first pic of the back if an alternator I could find.
Thanks very much for the explanation sir!

Down

Bill, thanks again for the tip. I just went out and took some measurements with my multimeter and this is what I found:
Battery with car off: 12.1
Battery with car running and blower on high: 14.52
Alternator with car running and blower on high: 14.66

I started getting the Charging System Fault/Service Engine Soon light right after a long tube install. I replaced the battery and the situation remains unchanged. The engine grounds will be getting inspected/cleaned if necessary soon but in your opinion, how likely is it to be a bad connection at the starter solenoid given the difference in readings between battery and alternator and the recent activity around the starter with the LT install?
just trying to temper my expectations on how involved this resolution will be.
Thanks in advance for your help!

Bill Curlee

Voltages look excellent BUT,, the solenoid would be the first place that I would check

Bill

Down

Really appreciate your input.