webdzynes

About a month ago my voltage dropped to 11 volts and continued to drop a tenth or so every 10 minutes down to 10.1 volts and then popped back to normal at 14.2. No apparent reason for any of it. Been fine since - until today. Went to start it and its read 10.9 volts. I decided to drive around the block and it dropped to 10.8, 10.7, 10.6 to 10.5 when I got back home about 5 minutes later. I'm in Florida and so batteries are frequently replaced also. Car has 122k miles. I'm thinking I should put the battery on a charger to ensure its fully charged and run down to pepboys to have them check both, about 10 miles away. If the alternator stops altogether, will a full battery get me there and back or am I risking being stranded?? AND, any recommendations on where to get a new (or rebuilt) alternator??

Cherokee Nation

Check around your area for a starter and alternator rebuild shop is what i would do.You will save a lot of $$$$.

owc6

Autozone, ten minutes if you have two people (four hands); twenty minutes if doing by yourself.

This is actually one of the easier jobs on a C6.

the kid C6

You'll probably be okay, but there are worse places to be stranded than Pep Boys.

The last time I had an alternator go (not the Corvette), the dash lit up like a Christmas tree. I was told I could drive it and probably make it home, but it was dark and there wasn't enough left in the battery to run the headlights.

You know how to get out of the Corvette when the battery's dead, right?

Garry in AZ

Check the connections on the starter. The output of the alternator is routed to the battery terminal on the starter and if the connection is poor, an intermittent charge condition can occur. While you're at it make sure all your grounds are tight as well, and the alternator case is properly grounded.

subfloor@centurytrans

It's been my experience that alternators generally go bad and stay bad, they won't cause a voltage fluctuation like the one you're seeing. What will however cause that is a cracked starter solenoid. The problem though is that you pretty much have to pull the entire starter to see if that's the problem.

The good news however is that if it's the solenoid that's bad you can get a replacement from Amazon without having to buy the entire starter.

Dano523

Alternator is pretty easy to pull apart and clean/rebuild, and if the problem is the alternator, would dare to guess that your at the end of life of maybe a brush or two, one of the brushes is packed to hell with dust to cause it to stick inwards, or split ring surface is carbonized and needs to be cleaned.

https://www.corvetteforum.com/forums...nator-fix.html


Hence easy way to check to weed out if its the alternator, or something down line instead, is to just do a voltage reading on the charging system with the fan off, lights off, and the motor idling with a multi meter set to DC voltage.

Body of the alternator as the ground, back terminal under the rubber boot as the positive source for the meter, should be getting a 14.7 volt reading.

Next on the battery lugs as the positive and negative source for the meter, should have a reading of about 14.5 volts.

From here, open the fuse box lid and engine fuse block terminal post as the positive source, and the body of the alternator as the negative source, should have 14.5 volts as well.
Note double check the engine fuse box terminal nut, since it may be loose to cause problems!

If the battery terminals reading is low, but fuse box to alternator ground is 14.5 volts, then the engine block ground just above the starter has a bad connection.

If the terminal test, and the fuse box/alternator test are both low, then problems on the positive wire side at the starter solinoid the problem isntead (where the positive wire from the battery, and postive wire from the alternator bolt together).

If the initial alternator test is low, then alternator itself.
Note, here, there are two voltage sources to the alternator, so make sure the horn still honk since it one of the voltage source, then check the alternator fuse source in the fuse box as well.

Also, if all three check out fine, but when you check the voltage on the dash/DIC is below 14.3 volt, then a problem from the engine fuse box, through the BCM, then to the ECM. Hence engine dash is telling you the voltage of the ECM for both, and again, voltage goes from the engine fuse box, to the BCM and it fuses, then to the ECM. If you have problems here, then pull upper engine fuse box to clean it and its lower blocks, the BCM connectors, and them the ECM connectors.
Note, if you have a tech ii, it easy to take a voltage reading of all the Modules, and this allows you to check all the modules and there connectors to see if one of these connectors or it ground wires need to be checked as well.


As for some of the rebuilt alternators, its a total crap shoot with the OEM valeo units. Hence problem is not the voltage regulator, or even the brushes that get replaced during the rebuild, but the unit at some point was over spun, this cracked the internal windings plastic basket, and this will cause the OEM alternator to be worthless from that point forward.

BLUEMEANIE

good info here
thanks!

Dano523

If you give me the voltage readings from the 4 areas listed above with the motor idling/ lights off.raditor fan not running (alternator, battery terminals, engine fuse box terminal to alternator body, and DIC voltage reading), I will tell you where the problem is, and how to correct it.

Hence once you know the system, it a snap to trouble shoot and correct the problem.