hey guys this message should tell you what im going through, i tried to PM it to bill but his box is full, so here it is for all of you to see.

Ive done some searching on the subject, and you seem to be the authority. my car that ive had for about 2 weeks now just very recently would give me a "charge system fault" on cold start in the morning but would go away after about 30 seconds and never come back. it only happend twice within these two weeks, now, today im about a mile from my house and my voltage spikes up to 15.0V and bounces between there and 14.8V. the charge system fault displays and this time, doesnt go away.. i continue to baby the car home and im watching my voltage drop all the way down to 10.6V, there, i believe the car tries to kick in the alternator and it shoots back up to 14.7 V and then drains off again.. I dont have a volt meter, but im not throwing any codes. ive looked around the passenger side header and visually inspected the starter wires, and they all look snug and corrosion-free. then i look around for the wire loom behind it ( as another member had a short there) and everything looks peachy keen, no burnt smells, no melted plastic. then i look at the alternator and it seems to be all good. there is a little rust in it and it seems to be the original alternator although i cant see a part number anywhere on it (i havent removed it or anything)... so do you have any ideas? im afraid to try to get it up to the autozone for them to test the charging system because i dont want whatever power I have to cut out on me and end up stranded. thanks!!! btw, this is my only car

 

oh btw, the battery is a red top newer style duralast battery so my guess was it was replaced within the last few years.

 

Sounds like it's alternator time. I can't think of anything in the battery or wiring that would make the voltage go up to 15 volts.

 

I took the battery out, went to get it checked, they charged it, it was good, i re-installed it, made sure everything was tight ( i noticed the negative terminal was only finger tight when removing it) fired her up. 13.7 V during warm-up 13.4-.5 at operating temps... ill keep everyone updated

 

Tiki I cleaned out the PM box. What year car do you have? It looks like there are at least 2 types of alternators. Have you checked the DIC for codes and have you checked the alternator output voltage right at the alternator when this fault was being displayed?

Bill

 

ive checked all the DIC codes and theres nothin. and the problem hasnt returned *yet*. my car is a 97.

 

Loose battery terminals will play hell with the PCM and the alternator!!! That was what I was going to recommend that you check. If your going to be doing any maintenance on your car, i strongly recommend that you purchase an inexpensive digital volt meter. By the way, the battery terminals need to be torqued to 11 ft/lbs as per the service manual.

BC

 

ill have access to a torque wrench this weekend, for now, they are tight via pliers

 

just got back from autozone.. they tested all my charging system for me while in car. diodes were good, regulator was good, but the poor lil alternator that couldn't is only pushing 36 amps and not 110. looks like i may get a little further on this lil guy, im guessing an alternator is in my near future. on the plus side, the harder i drive the car, the better my voltage looks. **sigh**

 

btw, does that sound right? i mean my diagnosis of the alternator starting to show signs that its on its way out the door.

 

When my alternator went bad I simply hooked a battery charger to the battery via external generator. Works great. It also took care of the the car's air conditioning which lost it's freon charge:

 

Unless they actually put a load on the alternator requiring it to put out it's max ability (110 amps), then their "reading" can be misleading. Alternators do not just "put out amps" (current) unless there is a demand for it to do so. Some testing equipment has the ability to vary the load placed on an alternator under test to see if it will respond appropriately within the design limits (110 amps max in this case) As the demand (load) increases/decreases the alternator will increase/decrease it's current (amps) output.
Since you are now sure you're cables are tight, give things a few days of driving to see how things go. You may have very well found the problem.

 

Just in case u end up considering a new alternator, check out this thread and read Evil Twin's info about alternators. To avoid a permanent charge sys fault, u will need to have yours rebuilt.

http://forums.corvetteforum.com/show....php?t=1530169

 

EXCELLENT recommendation!!!

 

well i noticed things were going well... for a while.. still no charge system fault, BUT, the autozone tester DOES creat a load on the alt to pull it to its max. heres the bad thing i noticed, every time i get in the car, my operating temp voltage has gotten .1 lower every time. so ive gone from 13.14-13.15 to 13.3-13.4 to 13.2-13.3 to 13.1-13.2 and when i turn the headlights and fogs and stereo on, i drop to 12.6-12.8. how much does it run to get your alternator rebuilt? I looked up the GM part number on GMPARTHOUSE.COM and they seem to carry the right alternator for $285. thanks guys.

 

unless that voltage behavior sounds normal haha. but i do go up to about 14.2 V if im .... driving spiritedly.

 

Since your system voltage is showing a gradual but consistent trend downward, it may very well turn out to be the case that a new alternator is in order. That system voltage of 12.6-12.8 at idle is low. Even with lights, etc it should be more like a full volt higher (approx.) Don't rule out a faulty battery either, especially if, as you say, it's a few years old. If it won't accept a full charge, that can cause headaches too.

 

The autozone test showed that with a medium load on the alternator the output voltage dropped quite a bit as it delivered 36 amps. That is a pretty good indication something in the alternator has gone south. Now it is just a matter of how long it takes before it completely fails.

Bill

 

Not sure about the $$ to rebuild your alt, but hopefully by getting the exact part # mentioned in the post from Evil Twin will avoid what I have now! Let us know how it turns out plz.

 

I sincerely hope this is a joke ! Does this person live in their car? Putting a window air conditioner in a car window is crazy !