New Generation N62 Engine
Chapter 3 P.24
Course Contents/Background Material
© BMW AG,
Service Training
The connection with the DME makes it possible to almost
completely equalize the alternator load torque. This supports the
engine idling speed control system, and the battery load
balance can be improved thanks to this intervention in the
engine management system.
In addition, the DME receives information from the power
module fitted in the car about the battery's calculated tempe-
rature and charge status. This means that alternator
output can be adapted precisely to the temperature and load
status of the battery. This increases the battery's service life.
The charge indicator display strategy for the new BSD interface
alternators has not changed in comparison with the alternators
used until now.
Regulating the alternator torque, particularly when activating
Valvetronic operating motors, could cause headlamp power
fluctuations to occur. To prevent this, the headlamps are
supplied by an LSM (light switch module) with an 80 Hz cycle,
13.8 volt voltage.
A global temperature protection function is implemented in the
generator regulator. If the alternator overheats, the alternator
voltage is reduced until an appropriate temperature has been
set again in response.
Possible malfunctions/consequences
The DME can recognize the following faults:
- Mechanical faults such as blockages or belt drive failure
- Electrical faults such as exciter diode defects or over/under-
voltage caused by regulation defects
- Connection defects between the DME and the alternator
Coil breaks and short-circuits cannot be recognized.
Basic alternator function is also guaranteed even if the BSD
interface fails.
