* Alternator Failure: This is the most likely culprit. The alternator might be failing to generate sufficient voltage, or it might be completely dead. This could be due to a bad alternator, worn brushes, faulty diodes, or a broken belt.
* Loose or Broken Belt: The serpentine belt (or V-belt, depending on the exact model) drives the alternator. If it's loose, slipping, or broken, the alternator won't spin and won't charge the battery.
* Bad Battery: While a dead battery will initially cause the light to come on, if the battery is very weak or has internal shorts, it can prevent the alternator from charging it correctly, leading to the light staying on.
* Wiring Problems: A break or short in the wiring between the alternator, battery, and the warning light circuit can also cause the light to stay on. This includes corroded connections.
* Voltage Regulator Issues (if applicable): Some older systems had a separate voltage regulator. A faulty regulator could prevent the alternator from properly regulating its output. While less common in '72, it's worth considering.
* Ignition Switch Problem: Though less likely, a faulty ignition switch could affect the charging system's circuit.
Troubleshooting Steps:
1. Check the Battery: Test the battery's voltage. A low voltage reading suggests a charging problem or a bad battery.
2. Inspect the Belt: Look for a broken, loose, or significantly worn serpentine belt.
3. Check the Alternator: Visually inspect the alternator for any obvious damage. A mechanic can test the alternator's output using a multimeter.
4. Examine Wiring and Connections: Look for any corroded, loose, or damaged wiring and connectors related to the alternator and battery.
5. Listen for Whining Noise: A whining noise from the alternator might indicate a bearing problem.
If you are not comfortable working on car electrical systems, take your Chevelle to a mechanic for diagnosis and repair. Driving with a faulty charging system can leave you stranded with a dead battery.
