Possible Causes:
* Faulty Alternator (Despite Being New): Even brand new alternators can be defective out of the box.
* How to Check: Use a multimeter to test the alternator's output voltage while the engine is running. It should be around 13.5-14.5 volts. If it's significantly lower, the alternator is likely faulty.
* Faulty Battery Cables: Corrosion or loose connections on the battery cables can prevent proper charging.
* How to Check: Inspect the cables for corrosion and ensure they are firmly connected to the battery terminals and alternator. Clean any corrosion with baking soda and water, and tighten the connections.
* Faulty Voltage Regulator: The voltage regulator is part of the alternator that controls the charging output. A faulty regulator can lead to undercharging.
* How to Check: Some alternators have a separate voltage regulator. If you have one, it might be a good idea to replace it.
* Faulty Wiring: A break in the wiring between the alternator and the battery, or between the battery and the fuse box, can interrupt the charging circuit.
* How to Check: Visually inspect the wiring harness for any signs of damage. You can also use a multimeter to check for continuity in the charging circuit.
* Faulty Battery: While you mentioned a new battery, it's possible it's defective or damaged.
* How to Check: Have the battery tested at an auto parts store to confirm it's holding a charge properly.
Troubleshooting Steps:
1. Test the Alternator: Use a multimeter to check the output voltage of the alternator while the engine is running. If it's significantly lower than 13.5-14.5 volts, the alternator is likely faulty.
2. Inspect Battery Cables: Check for corrosion and ensure the connections are tight.
3. Check the Wiring: Inspect the wiring harness for any damage or loose connections.
4. Test the Battery: Have the battery tested to rule out a faulty battery.
Important Considerations:
* Safety First: Always disconnect the battery before working on the electrical system.
* Multimeter: A multimeter is an essential tool for diagnosing charging problems.
* Professional Assistance: If you're not comfortable troubleshooting electrical systems, it's best to take your vehicle to a qualified mechanic.
Let me know if you have any more questions or need further clarification.
