will69camaro

iTrader: (19)

So about a month ago my HO SS is sitting in a drive thru lane and my "check gauges" light comes on, i look at my voltmeter is sitting around 9ish. I rev to see if it will come up any and it doesnt' budge. I figure no biggie i'll just replace the alternator that weekend. I pull the alternator and take it down to have it tested and it tests good...a few times and they let it run awhile and nothing appears to be wrong with it. So I reinstall it and make sure the connections are good on the alternator side and start the car back up and the voltage is low but not as low (around 10-11). I have my gf start it as i listen for any arcing etc... She revs it and voltage goes up to normal spot (14 maybe a little higher). Car stays that high for the next few weeks (dont drive much though) and on my drive back to Midland from College Station i get about 300 miles in and all the sudden it drops to 10 volts, lights dim etc. I proceed to drive to see how far it will make it and voltage pops back up to 14+...The rest of the drive home the voltage kept going from 14-10 and dancing inbetween. Does anyone know what this might be? I'm thinking bad connection somewhere but not sure where. Also if it makes any difference it has an optima in it.

William

will69camaro

iTrader: (19)

Anyone have any experience with anything similar?

Thanks,
William

Dale Schulz

I start my firebird once a week. About 2 months ago my alternator was making a grinding sound and gauge was showing 9 volts. Drove car 2 mi. and grinding sound stopped as well my gauge started charging normal also. Now every other week alternator will do same thing but goes away after 2 mi. I have no codes and so I am just watching it. I don't know what to do. It has not ran my battery down.

will69camaro

iTrader: (19)

yea mine doesn't go away after 2 miles, i drove it the rest of the drive (about 70 miles) with lights on and everything back to my house...Hope i can figure it out, just waiting for it to warm up some!

William

will69camaro

iTrader: (19)

Update:

Battery is good, checked all connections on battery and they're good as well. Checked where the union is at the fuse box from the wire going to the battery and the wire coming from the alternator and it's good. I will start chasing it down with a multimeter shortly but i'm starting to think it's the alternator...

William

will69camaro

iTrader: (19)

Ok more questions. I changed alternator and it worked for a little while (maybe 25 miles) then started dropping again. Battery has tested good, alternator has been changed and it still does it. What else can i change to help get rid of this problem? I need to try and chase it down. Does the PCM tell the alternator when to turn on (charge) and when not to? Could i have a problem with my PCM?

William

2K2WS6TA

iTrader: (2)

So where did you get the replacement alternator, I've had several (5) that failed fairly quickly (tho 25 miles is ), they were the typical parts store remans, so you may have gotten a bad alternator (if you indeed did buy a replacement)

thebatman411

iTrader: (4)

My guess would have to be the alternator. Maybe that replacement is a referbished one. I had this same identical problem 2 days ago. I also took off the alternator and had it tested and it showed that it was good. So I put it back on and the same crap. So this time I drove the car to the shop that tested my alternator and checked all my wires and they told me that it must be the alternator. The guy apologized for making me put it back on. Anyway, I took off the alternator and dropped it off to get repaired and it works fine now. I had the same identical problems you have with the voltage dropping and then working fine, but then dropping again. Instead of buying a new alternator, you should return the replacement, get your money back, and have the original one completely repaired at an electrical shop. I'm guessing that replacement is a cheap one from auto zone. Just go with the original with all new parts.

will69camaro

iTrader: (19)

Ok, that's what a friend of mine told me to do and i wanted to try a replacement (cheap Orielys one). There is a shop that he suggested so i'll just take this one back off and take the old one in to be repaired. Hopefully this will solve my problem because i like driving my new car and cant ever get a chance to! Thanks for the advice guys and i'll keep you posted!

William

thebatman411

iTrader: (4)

I'm sure repairing the original will solve your problem. Once you slap on your repaired alternator, you'll be keeping a close look at the voltage. And you'll probably even think that the voltage is going down, but it'll probably be your mind playing tricks on you. After I installed the repaired alternator it looked like that voltage was going down, but it was just me being all freaked out. Here's a good indication of a working alternator: turn on your blinker. If the voltage pointer on your gauge is slightly moving back and forth then your alternator is working. Update us on the results and good luck.

will69camaro

iTrader: (19)

Will do, i dropped off the original and will be picking it up tomorrow and replacing the replacement and returning it. Hopefully this will solve my problem! Thanks for the help guys. Also where does the voltage pointer point on a good working system?

William

thebatman411

iTrader: (4)

Mine usually sits about 3/16 to the right of the middle mark which is about 14 volts.

will69camaro

iTrader: (19)

Ok more questions. I have since checked grounds, connections to the alternator and had the factory one rebuilt. It still did it once and the gauge jumps around sometimes. Does anyone know where that wire goes from the plug to the alternator or have a wiring schematic showing where it goes? Is it a switch 12v source? I checked mine and it was 10.6V when the battery was showing 11.9V. If it's just a switch 12v i might just rewire the damn thing since that's about all it can be now. I've changed/checked everything.

Thanks,
William

will69camaro

iTrader: (19)

Cliff-notes if that's too long...Where does the red wire from the plug in the alternator go? Surely someone knows...

William

Moparnos (The SLP Guy)

iTrader: (55)

check your wiring from alt and battery cables really good i had the same problem it ended up being the positive cable that goes to the alt. good luck

will69camaro

iTrader: (19)

Checked those, they're perfect...Monster cable from battery to post at fuse box and wire that tests good from there down to alt....

William

thebatman411

iTrader: (4)

damn dude that sucks. I thought it was the alternator for sure. I wish I could give you more advice, but I don't know what else to check. It may be time to take the car to an electrical shop and have them figure it out. Hope you get it solved.

will69camaro

iTrader: (19)

This pisses me off royally, i cant get it fixed and no where can i find out where that damn wire goes. I know probably the best EE in the area and he's willing to help me for nothing but we need to figure out where that wire goes and how much voltage a proper working system is supposed to show.

William

will69camaro

iTrader: (19)

New question, is the gauge supposed to move when i put my blinker or my lights on? When i turn my lights on manually the gauge drops to around 13V then goes back up to 14ish...

Thanks,
William

WS6store.com

iTrader: (30)

How did you check the positive wire from the battery to the alternator? A lot of times people will just check resistance, when in fact the best test is a voltage drop test while the vehicle is running. Also check the ground wire for voltage drop between the alternator casing and the battery negative terminal. Both voltage drops should be very low around 0-0.1 volts volts. If it's over 1 volt you have a bad wire needs to be replaced. Report back with your measurements.