SIB-12-12-13

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SB-10052358-7413
SI B12 12 13
Engine Electrical Systems
May 2013
Technical Service
SUBJECT
N52T Alternator-Related Malfunctions: Overcharging or Undercharging
MODEL
F10
F25
With the N52T engine
SITUATION
Many different complaints may arise from alternator-related malfunctions, due to charging sporadically or not
charging at all, for example:

Electrical consumers no longer work or are switched off.

Various warning lamps such as EGS, DSC, ABS, etc., illuminate.

Electrically assisted steering feels stiffer.

The alternator is not charging or causes an overvoltage in the vehicle electrical system.

The battery is discharged or has been overcharged due to an overvoltage charging condition.

The engine may cut off depending on the battery state of charge, but a restart is possible.
These problems occur intermittently when the engine is at operating temperature and the following faults are
found stored in the DME fault code memory:

CD9304 – Bit-serial data interface, signal: communication fault
and

213301 – Power management, overvoltage: Overvoltage detected
and/or

213401 – Power management, undervoltage: Undervoltage detected
CAUSE

A faulty ignition coil disrupts the alternator temporarily: the alternator is not defective.

A faulty ignition coil disrupts the alternator frequently: the alternator is defective.
Note: There is no fault code entry in the DME memory for the faulty ignition coil.
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CORRECTION
1. Perform all recommended test plans with ISTA/D.
2. Check the Bit serial data interface bus (BSD) in accordance with test module:
AT1214_BSD – BSD Communication
3. Replace all ignition coils (even if a fault was found on the BSD bus).
4. With the new ignition coils installed, manually bring up the alternator test module and perform the
“Function test”:
AT1214_TVD_GEN – Alternator
The path to this test module (the filter has a check in the Procedure [ABL] box) is:
Functional structure / 03 Body / Voltage supply / Alternator
Only replace the alternator if this test module instructs you to do so.
5. Charge and check the battery.
6. Clear the fault memory.
WARRANTY INFORMATION
Not applicable.
[ Copyright ©2013 BMW of North America, Inc. ]
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