1. Verify the New Alternator Installation:
* Wiring: Double-check all wiring connections to the new alternator. Loose, corroded, or incorrectly connected wires are common culprits. Pay close attention to the positive (+) and negative (-) connections. A reversed connection can damage the alternator and the electrical system.
* Belt Tension: Ensure the serpentine belt is properly tensioned and not slipping. A slipping belt won't drive the alternator. If the belt is worn, cracked, or glazed, replace it.
* Alternator Ground: A poor ground connection can prevent the alternator from functioning correctly. Clean the ground connection points on both the alternator and the engine block. Use a wire brush and ensure a good metal-to-metal contact.
2. Test the System:
* Battery Voltage: With the engine OFF, measure the battery voltage using a multimeter. It should be around 12.6 volts. A lower voltage indicates a weak battery.
* Voltage with Engine Running: Start the engine and measure the voltage again. It should be significantly higher, ideally around 13.5-14.5 volts. If it remains around 12 volts or lower, the charging system still isn't working.
* Alternator Output (Advanced): If you have the appropriate tools, you can test the alternator's output directly. This usually requires disconnecting the alternator and using a multimeter to measure the voltage and amperage while applying a load. This is a more advanced step and requires some electrical knowledge.
* Check the Battery: Even with a new alternator, a bad battery can prevent charging. Get your battery load tested at an auto parts store.
3. Other Potential Problems:
* Voltage Regulator: The voltage regulator, either internal to the alternator (some are) or a separate component, controls the alternator's output. A faulty voltage regulator can prevent the alternator from charging properly.
* Wiring Harness: Damage or corrosion in the wiring harness between the alternator and the battery or the PCM (Powertrain Control Module) can interrupt the charging circuit.
* Fuses and Relays: Check the fuses and relays associated with the charging system in the fuse box. A blown fuse or a malfunctioning relay will prevent the alternator from working.
* PCM (Powertrain Control Module): In some cases, a faulty PCM can prevent the charging system from functioning correctly. This is less likely, but possible.
If you're not comfortable performing these tests yourself, take your Cadillac to a qualified mechanic. Improperly diagnosing and repairing electrical systems can lead to further damage. They have the tools and expertise to accurately diagnose the problem and make the necessary repairs.
