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Issue: Started with battery light flashing and voltage dropping while driving (have gauge in cigarette plug). Issue was intermittent to start. Sometimes it did it. Sometimes it didn't. When it did it, after around 10 minutes it would stop having a blinking light and start charging at 14.3 V. Eventually the battery light stopped blinking but the voltage still seemed rather low. The latest time, the car never started charging and the battery drained down to around 8.8V when I arrived home and couldn't restart the car.
Resolution: After arriving home, I charged the battery and ordered a new alternator (aftermarket off amazon). I installed the new alternator and turned the car on for a second, reading 14.3V. Perfect. 10 min later I could out to move the car and it would only give around 11.6 without any accessories on. Turned the headlights/AC on and it would drop to 10.6, Took the car assembled to the auto store (O'Reily's) to have the alternator checked. They said the alternator had a bad voltage regulator so I ordered a new alternator (AcDelco New). This time I had it benched tested by the auto store prior to installation. Bench tested showed the 2nd alternator was good. Installed this alternator and still around 11.6 volts and drops significantly with lights/AC.
Finding the electrical diagram below, I start to test other components:
- I removed the battery and bench tested that. Good battery. I swapped in another battery and issue did not resolve.
- I checked all fuses (underhood and underdash) and none are blown.
- I ordered a new ELD and swapped. No difference.
Knowing these these components are good, I started testing the electrical wiring.
- I tested voltage drop from alternator stud to battery. 0.003V. Pass.
- I cleaned the trans, engine block, and body connections to ensure good grounds. I checked the alternator body for grounding with low (under 10 ohm) resistance.
- I tested ELD connection. The left wire was 11.56V (supposed to be 12V), middle wire 0 V (ground), and the right wire was 4.6V (supposed to be 0-5V). Pass
- I checked the voltage of black/yellow wire at alternator plug. 11.56 V.
- I tested a ground out of the stud by removing the positive battery terminal from the battery and check against ground. No connection.
- I checked if any of the four wire on the green alternator plug grounded out, 2 of the four did. I wouldn't expect the wire to the PCM to ground out with ignition off. Is this normal?
After all of this, I do not know what else to check..... help....
I thought you guys were crazy, but I didn't have any other options so I went to the pick n pull, grabbed an alternator, and for a week or two it was running perfect. Charging 13.9 to 14.3 across all driving conditions and loads. Last night, I got in the car to drive home and the car was reading 11.6 across the drive with headlights and AC on. I know these cars do funny things to protect fuel economy, but I feel this is dropping a little too low.
Is this behavior common? Should I be concerned? Is there other checks I can do?
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Re: Charging Issues
Originally Posted by welcometomylehr
Is this behavior common? Should I be concerned? Is there other checks I can do?
Find related info in the service manual or call a dealer (mechanic) to confirm voltage range to load conditions. Do you have an ammeter to check amperage? If not, (iirc) most parts store can check amperage.
Charging Issues 
