Alright to start off I have a 1989 Camaro IROC-Z28 with a 305TPI it has a 5 speed manual.

During the summer monthes I was driving it down the highway and the alternator died and caused my battery to die. Luckily I work at napa and just got it replaced however while I was replacing it the powersteering/alternator bracket busted on the top mounting hole I drove around with it like that for a while without any issues however I wanted to get it fixed when I could afford it and after a while I started to have some charging issues so I just last week finally replaced it because I thought it was the cause to the alternator not putting out a good charge.

So now I have a brand new mounting bracket so it is very stable. I also replaced the alternator under warranty just in case and it has a brand new alternator on it now. It also has a brand new battery and I have checked the resistance in the wires and all of them read at .5 ohms which is perfect continuity and all of the wires have great connection to their destinations I guess you could say.

So you would generally say I have a perfect charging system however when I start the car the alternator charges at 14 volts which is a bit high but still not bad but once I start driving it drops down to 11 volts and unless the battery is completely charged the car will inevitably die after a little while. I have checked/replaced everything and everything should run perfect but it obviously doesnt. I was wondering if anyone has any ideas or has ran into this situation before because I am completely stumped.

Thank You in advance

 

Replace the alternater again. Some parts stores have crappy rebuilt electrical parts.

 

Its not the alternator I have replaced it 3 times now and they have all been brand new premium napa alternators with relatively recent manufacture dates and have all been bench/stress tested and all readings have been taken by my multimeter and my guage presents an accurate reading according to the multimeter the only thing that I can think is that somewhere the ecm is telling it that it doesnt need much voltage and the regulator inside the alternator is changing the voltage or something similar so i am not sure what it is

 

BUMP: Any Ideas? My best guess is that the ecm is sending the voltage regulator inside the alternator the wrong signal so if someone knows of something that might cause this cuz the ecm is perfect had it tested also

 

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14v is not at all high most run around 14.4 to 14.8

 

Alright well first thanks im gonna check for a short tomorrow morning
second the issue isnt the 14.95 volts that the alternator kicks out its the 11 that it drops down to I know its too low thats why its an issue and the reason i said 14 was high is because optimum performance is from 13.8 to 14.3 in which 14.95 is a bit higher than normal not saying it was too high... but thank you for your help if there are any other ideas they would be helpful ill post how my search for shorts goes

 

I'm have the very same issue with an 87 GTA. Car will run after I have charged the battery, then will die when the battery is dead. I have replaced the alternator also. Stumped!

 

Check the connections on the back of the alternator and starter to make sure they are tight, also ( longshot ) check all of your grounds especially the ground strap going to the motor.... You'd be surprised some of the problems a faulty ground can cause! I hope this helped you and i hope you find the problem! If you do please post to let everyone know what was wrong....

 

Well I disconnected all the cables on the battery, alternator, starter and ground. Wire brushed the ends and re-tightened. Went for a 30min drive with lights on with no problems and the battery gauge showed about 15. I hope we got the problem. Thanks.

 

i had the same thing happen to my 91rs voltage was around 14 but would drop to 12 after 4 or 5 minutes, i replaced 3 alternators, turned out it was a blown fuse good luck

 

i had a very similar problem it happened to be the wire off the alternator one of the trigger wires was bad in the fuse box it wasnt making good contact so you might want to check that

 

i would start at the alternator check voltage at the back second the thick wire on the side shoud be hot (12v) with igntion on this lets the alternator charger at low rpm and also check body ground.small wire off ground to battery to fender, thick wire to engine.

 

Hey I completely forgot about this post I have fixed the problem my issue turned out to be that the wire coming from the alternator plug was loose inside the plug (of course the last thing i check) everything is running perfect after I replaced the plug no issues as for others with similar problem I will list everything i did so you can look where to start

HELPFUL DIAGNOSTIC TOOLS
1 Multimeter
2 Wiring Diagrams

CHECK WIRES IN ALTERNATOR PLUG!!! LOL
Change Battery
Change alternator
Check Fuses
Check Battery cable terminals
Check the alternator mounting bracket
Check the battery cables (including battery to alternator) continuity using a multimeter should only have between .3 and .7 ohms of resistance if zero you have a short to ground or not reading it right
Check Cable Connection at starter
Check the fusible links from the starter
Check For battery draw using multimeter
Check connection at any relays or switches connected to the alt/starter (ex. clutch starter switch)
Check Belt tension

If you do all of this you should find the problem because when i stumbled upon the plug it was only because i knew when I unplugged it and plugged it back in it would charge for a second (thats why multimeters are handy) and then jiggled the wires and realised the problem but it was all in a last ditch effort cuz i couldnt figure it out I had done everything...

Hope this helps

 

I had a charging issue on one of my other cars like this. Replacing the alternator does not help if the fault is not with the Alt. Since you have replaced it 3 times the alternator is not at fault.

My guess is the battery cables.

Check your volts on the back of the alternator. Then check your voltage on the end of the wire that runs from the back of the alternator to the battery. If there is a voltage drop along that wire you know you need a new one.

These wires do build up resistance over time and will cause charging issues just as you describe.