On-board electrical system
Networking
71
Introduction of the New E-Class Coupé, Model Series 207
b
The consumer reduction function is canceled as
soon as the alternator is again able to provide the
requested electrical output to stabilize the on-board
electrical system.
A special case of consumer reduction is
on-board
electrical system limp-home mode
. This is acti-
vated by the on-board electrical system manage-
ment in the rear SAM control unit if the on-board
electrical system voltage drops below U = 10.6 V
for t = 10 s. The following functions of energy
management driving mode are activated:
• Idle speed increase
• Deactivation of alternator management
• Consumer reduction with shutoff of short-term
power consumers
The consumer power reduction or shutoff occurs
with a cycle period of t = 200 ms.
Dynamic idle speed control
The dynamic rpm increase is intended to adjust the
idle speed of the engine so that no power is drawn
from the on-board electrical system battery while
idling. Accordingly, when consumer load is high, a
high idle speed is set. In contrast to the previous
rpm increase function, which takes effect when the
voltage drops below a given limit or when a certain
consumer shutoff stage is reached, the dynamic
idle speed control is intended to act preventively.
Therefore it does not react to a lack of electrical
energy, but determines in advance the necessary
idle speed for the current load.
The required idle speed increase is computed via
the on-board electrical system control in the rear
SAM control unit and forwarded to the CDI or
ME-SFI control unit. This calculates the idle speed
that is actually required, taking into account various
engine characteristics.
P54.10-3191-00
Main components of on-board electrical system, shown on the E 350 CGI
B95
Battery sensor
F32
Front prefuse box
G1
On-board electrical system battery
G2
Alternator
N3/10
ME-SFI [ME] control unit
N10/2
Rear SAM control unit with fuse and relay
module
– This printout will not be recorded by the update service. Status: 01 / 2009 –
