12 31 009 Checking alternator (BSD)

WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 2013 BMW 328xi, 2013 BMW 328i, 2012 BMW 328xi, 2012 BMW 328i, and 2011 BMW 328xi. However, it is still accessible from the selected car via links, so may be relevant.

Necessary preliminary tasks:

Correct connections on charged battery
Correct connections on alternator and starter motor
Good ground connection between engine and body
Tensioned ribbed V-belt
Read out DME/DDE fault memory.

NOTE: The alternator with BSD interface can communicate with the engine control unit (DME/DDE).

The alternator is not connected to the charge telltale light.

The alternator can identify various faults.

BSD alternator can be recognized by the plug connection on the alternator.

Connect diagnosis tester.

Function selection
Complete vehicle
Drive
Voltage and current regulation
Voltage and current generation
Alternator
Follow instruction in diagnostic program

Oscillogram for a fault-free alternator:

Fig 1: Fault-Free Alternator Oscillogram Graph

G04740394

Courtesy of BMW OF NORTH AMERICA, INC.

Oscillogram for a faulty alternator:

One phase interrupted.

Repair/exchange alternator.

Fig 2: Faulty Alternator Oscillogram Graph (One Phase Interrupted)

G04740395

Courtesy of BMW OF NORTH AMERICA, INC.

Interturn fault.

Repair/exchange alternator.

Fig 3: Faulty Alternator Oscillogram Graph (Interturn Fault)

G04740396

Courtesy of BMW OF NORTH AMERICA, INC.

Open circuit in negative diode.

Repair/exchange alternator.

Fig 4: Faulty Alternator Oscillogram Graph (Open Circuit In Negative Diode)

G04740397

Courtesy of BMW OF NORTH AMERICA, INC.

Short circuit in positive diode.

Repair/exchange alternator.

Fig 5: Faulty Alternator Oscillogram Graph (Short Circuit In Positive Diode)

G04740398

Courtesy of BMW OF NORTH AMERICA, INC.

Open circuit in positive diode.

Repair/exchange alternator.

Fig 6: Faulty Alternator Oscillogram Graph (Open Circuit In Positive Diode)

G04740399

Courtesy of BMW OF NORTH AMERICA, INC.

Open circuit in exciter diode.

Repair/exchange alternator.

Fig 7: Faulty Alternator Oscillogram Graph (Open Circuit In Exciter Diode)

G04740400

Courtesy of BMW OF NORTH AMERICA, INC.

Assemble engine.

Check function of DME/DDE.