Disconnect the negative battery cable
Inspect the alternator belt for wear, looseness, or damage
Tighten or replace the belt if needed
Check the alternator electrical connections for corrosion or looseness
Clean the terminals and reconnect them securely
Test the battery voltage with the engine off and running
Replace a weak or failing battery if necessary
Check the alternator fuse and replace it if blown
Inspect the wiring harness for damage or breaks
Replace damaged wires or connectors
Remove the alternator from the vehicle
Test the alternator with a multimeter or bench tester
Replace worn brushes, bearings, or voltage regulator if serviceable
Reinstall the alternator and secure all mounting bolts
Reconnect the belt and set proper tension
Reconnect the battery cable
Start the engine and verify charging voltage
Replace the alternator if it fails testing or cannot be repaired