Bosch (OE Reman) AL9407X Alternator; 120 Amp – BMW | 12317830791 12317831436 W01331665003

The alternator on your BMW is an electrical generator used to charge your vehicle’s battery and power your vehicle’s electrical components. As the alternator spins, an electromagnetic coil rotor spins creating an electromagnetic field and allowing the stator to generate an alternating electrical current. The alternating current is converted by a rectifier regulator into a direct current that can be used by your vehicle.

A faulty alternator will either not produce any electricity or will not produce enough electricity to power your BMW or charge the battery.

Signs of a Faulty BMW Alternator

• A dead battery after driving
• Surging lights or other electrical systems surging from a lack of electricity
• A whining from the alternator when the engine is running
• Illumination of the battery warning light in conjunction with the brake warning light to indicate the alternator is not producing electricity

Replacing a Failed BMW Alternator
Replacement of your BMW alternator should only occur if the alternator has failed or is damaged in any way.

The location of the alternator will vary from vehicle to vehicle, but it is almost always mounted near the front of the ngine and driven by a serpentine belt attached to the engine crankshaft. Because of the varying locations, replacement of the alternator can take anywhere from 30 minutes on vehicles with the alternator mounted openly to several hours for alternators mounted deep inside the engine bay.

BMW Alternators.