12 31 009 Checking alternator and regulator switch

WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2005 BMW 325xi, 2005 BMW 325i, 2005 BMW 325Ci, 2004 BMW 325xi, and 2004 BMW 325i. 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.

Fig 1: Checking Carbon Brushes

G03164316

Courtesy of BMW OF NORTH AMERICA, INC.

Replace alternator regulator switch, refer to 12 32 501 REPLACING VOLTAGE REGULATOR (VALEO/BOSCH) .

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

If charge indicator lamp goes out while engine is running, check control voltage: 14.3 V.

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

Replace alternator regulator switch, refer to 12 32 501 REPLACING VOLTAGE REGULATOR (VALEO/BOSCH) .

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 Fault-Free Alternator

G03164317

Courtesy of BMW OF NORTH AMERICA, INC.

Oscillogram For A Faulty Alternator:

One phase interrupted.

Repair/exchange alternator.

Fig 3: Oscillogram For Fault-Free Alternator (One Phase Interrupted)

G03164318

Courtesy of BMW OF NORTH AMERICA, INC.

Interturn fault.

Repair/exchange alternator.

Fig 4: Oscillogram For Fault-Free Alternator (Interturn Fault)

G03164319

Courtesy of BMW OF NORTH AMERICA, INC.

Open circuit in negative diode.

Repair/exchange alternator.

Fig 5: Oscillogram For Fault-Free Alternator (Open Circuit In Negative Diode)

G03164320

Courtesy of BMW OF NORTH AMERICA, INC.

Short circuit in positive diode.

Repair/exchange alternator.

Fig 6: Oscillogram For Fault-Free Alternator (Short Circuit In Positive Diode)

G03164321

Courtesy of BMW OF NORTH AMERICA, INC.

Open circuit in positive diode.

Repair/exchange alternator.

Fig 7: Oscillogram For Fault-Free Alternator (Open Circuit In Positive Diode)

G03164322

Courtesy of BMW OF NORTH AMERICA, INC.

Open circuit in exciter diode.

Repair/exchange alternator.

Fig 8: Oscillogram For Fault-Free Alternator (Open Circuit In Exciter Diode)

G03164323

Courtesy of BMW OF NORTH AMERICA, INC.