12 31 009 Checking alternator and regulator switch

WARNING: This page does not describe the selected car, but rather 17 other vehicles, including the 2006 BMW 330Ci, 2006 BMW 325Ci, 2005 BMW 330xi, 2005 BMW 330i, and 2005 BMW 330Ci. However, it is still accessible from the selected car via links, so may be relevant.

Test requirements:

Correct connections on charged battery
Correct connections on alternator and starter motor
Good ground connection between engine and body
Tightened drive belt

Connect DIS Tester.

Measurement
Checking alternator

If charge indicator lamp is permanently lit:

Remove voltage regulator and check carbon brushes, replace if necessary.

Replace alternator regulator switch. See 12 32 501 Replacing voltage regulator (Valeo/Bosch)

NOTE: Minimum length of carbon brushes "A" = 5 mm.

Fig 1: Removing Voltage Regulator & Checking Carbon Brushes

G03123600

Courtesy of BMW OF NORTH AMERICA, INC.

If charge indicator lamp goes out while engine is running:

Check control voltage.

Regulator switch must be replaced if control voltage is not achieved.

Replace alternator regulator switch.

From E46/E39 with multifunction regulator.

Recognizable by plug connection on regulator.

Connect DIS Tester.

Function selection
Complete vehicle
Drive
Voltage and current regulation
Voltage and current generation
Work through test modules

Oscillogram for a fault-free alternator:

Fig 2: Oscillogram For A Fault-Free Graph

G03123601

Courtesy of BMW OF NORTH AMERICA, INC.

Oscillogram for a faulty alternator:

One phase interrupted.

Repair/exchange alternator.

Fig 3: Oscillogram For A Faulty Graph

G03123602

Courtesy of BMW OF NORTH AMERICA, INC.

Interturn fault.

Repair/exchange alternator.

Fig 4: Interturn Fault Graph

G03123603

Courtesy of BMW OF NORTH AMERICA, INC.

Open circuit in negative diode.

Repair/exchange alternator.

Fig 5: Open Circuit In Negative Diode Graph

G03123604

Courtesy of BMW OF NORTH AMERICA, INC.

Short circuit in positive diode.

Repair/exchange alternator.

Fig 6: Short Circuit In Positive Diode Graph

G03123605

Courtesy of BMW OF NORTH AMERICA, INC.

Open circuit in positive diode.

Repair/exchange alternator.

Fig 7: Open Circuit In Positive Diode Graph

G03123606

Courtesy of BMW OF NORTH AMERICA, INC.

Open circuit in exciter diode.

Repair/exchange alternator.

Fig 8: Open Circuit In Exciter Diode Graph

G03123607

Courtesy of BMW OF NORTH AMERICA, INC.