Mercedes-Benz S350 TURBODIESEL Operator's Manual page 85

Automatic Locking Differential (ASD)
The automatic locking differential
engages when there is a difference in
speed (slip) during acceleration between
the front and rear wheels of over 1.2 mph
(2 km/h) and the vehicle speed is less
than 15.6 mph (25 km/h). It will disen-
gage at speeds above 16.2 mph (26
km/h).
The yellow function indicator in the
speedometer comes on whenever there is
a difference in speed between the front
and rear wheels of over 1.2 mph (2
km/h), warning of slippery road
conditions.
In steering lock position 2, the yellow
function indicator lamp and the
yellow ASD warning lamp in the
instrument cluster should come on
and then must go out with the engine
running.
If the ASD warning lamp comes on
with the engine running, a
malfunction has been detected. We
recommend that you visit an
authorized Mercedes-Benz dealer as
soon as possible to have the ASD
checked.
Caution!
If the vehicle is towed with the front
axle raised, the key must not be in
steering lock position 2. Otherwise,
the automatic locking differential
control will immediately be engaged,
which may cause loss of towing
control.
Notes:
The automatic locking differential will
not engage at speeds above 15.6 mph
(25 km/h). However, above this speed,
a limited-slip effect of up to 35% is
always present.
When testing the parking brake on a
brake test dynamometer, turn off the
engine to avoid engaging the automatic
locking differential.
In winter operation, the maximum
efficiency of the automatic locking
differential can only be attained
through the use of Mercedes-Benz
recommended M + S radial-ply tires on
all four wheels.
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