I had my GTA die on me yesterday and sounded like a dead batt .
As it was sputtering then i turned my lights out and was able to make it home.
It makes me think the alt went south.
It started this morn na prabs.
What else would do this? Or is it for sure the alt?

 

If the battery isn't holding a charge, yes replace the battery.
If the alternator tests good, and the battery recharges fine, then I would check the battery terminals and get a clean connection.
My battery wouldn't charge, even though the battery was fine.
I was puzzled.
I could start the car, full charge from alt.
Battery would gradually die.
It turned out that the (-) cable had some acid on it, and it wasn't making a very good connection.

 

Is ther a easy way to check the alt!

 

Woody,

You can monitor the voltage directly at the alternator output stud with a DVM. With the engine running you should be generating at least 13.6 VDC - bare minimum.

To test maximum output, again with the engine running, locate the 'D' shaped test hole on the rear half of the alternator case, usually near the bottom mounting bolt boss. Inside the hole is a small metal tab that is part of the regulator assembly. Insert a small screwdriver into the hole to short the tab to the case (ground). This should override the regulator and force the alternator to produce maximum output (saturate the rotor windings). The voltage should jump on your DVM and peak well over 17.0 VDC. The alternator should also produce a high-pitched whine, indicating it is charging heavily.

WARNING: Only test the alternator with this method briefly, since the excessive voltage can damage other system components. You will likely also generate a "Code 53" DTC - System voltage over 17.1 Volts. Since you know why this code has occurred, you can disregard it.

If the voltage does not increase, either the regulator has failed or the alternator has problems (likely the brushes). You can repair your alternator for a negligible cost, or replace it with a remanufactured unit.

Be very wary of remans/rebuilt alternators and starters, and even water pumps, since the stamping on the outer case rarely indicates the actual internal components. Parts are mixed and matched at the rebuilder so you really never know what you have other than a working alternator that can produce some unknown level of output current. The same is true for starters and water pumps. I've seen water pumps with almost no vanes on the impeller being offered as a remanufactured unit for a car with heavy duty cooling. Yeah, whatever. I'll go somewhere else, thanks. The same happens with starter armatures and field coils. That "high-torque" starter may be a standard field and armature in a long case, so beware.

 

Thanks Vader