148 Starting and driving
All-wheel drive (AWD) 3
Essentially, the system consists of a PTU
(Power Take off Unit), propeller shaft, RDM
(Rear Drive Module which contains an elec-
tronically controlled plate clutch, final drive
gear and differential) and driveshafts. This
system enhances driving characteristics
and stability. The system is always active
and cannot be deactivated. It works
together with the ESP system and the
engine and transmission control modules.
When driving at a constant speed, approx.
95% of the torque is distributed to the front
wheels and approx. 5% to the rear wheels.
The torque is distributed steplessly and
instantaneously between the front and rear
wheels, depending on the driving condi-
tions. If the car is fitted with eLSD (electron-
ically controlled plate clutch between the
rear wheels), the torque can also be distrib-
uted individually to the relevant rear wheel.
For optimum system function, the car’s
tyres should not have varying degrees of
wear.
When the AWD system requires service,
the following message is shown on the DIC:
When the service message is displayed,
the AWD system may have limited func-
tionality (or be completely disabled in
some cases, i.e. the car switches to
front-wheel drive). Contact a workshop
for information. We recommend that you
contact an authorised Cadillac work-
shop.
Traction Control
System (TCS)
Anti-spin system
How the system works
The Traction Control System (TCS) is
designed to reduce wheelspin and so to
give the car the best possible tractive force,
together with enhanced driveability and
greater stability.
The TCS system uses information from the
ABS system’s wheel speed sensors to
determine whether any wheel is spinning. If
any wheel is spinning, this is reduced on all-
wheel drive cars initially by changing the
torque distribution, secondly by reducing
the engine torque, and thirdly with the aid of
the wheel brakes. On front-wheel drive cars,
wheelspin is reduced initially by reducing
the engine torque, and secondly with the aid
of the wheel brakes.
The advantages of the TCS system are
most apparent when road surface friction is
Service XWD.
WARNING
The TCS system improves stability and
driveability during normal driving, but it
must not be regarded as an opportunity to
increase the speed. The same precau-
tions as normal for safe cornering and
driving on slippery roads must be
adopted.
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