Porsche cayman gt4 Owner's Manual page 138

Examples of PSM control operations
– If the "front wheels of the vehicle drift" on a
bend, the engine power is reduced and the
rear wheel on the inside of the bend is braked
if necessary.
– If the rear of the vehicle swings out on a bend,
the front wheel on the outside of the bend is
braked.
– Brake booster (Hydraulic Brake Assist):
In the event of an emergency braking operation
where the pedal force is insufficient, a brake
booster provides the braking pressure
necessary for maximum deceleration at all
4 wheels.
136
Driving and Driving Safety
Automatic brake differential (ABD)
The ABD system controls the front and rear axles
separately. If one wheel of an axle starts to spin,
it is braked so that the other wheel on the same
axle can be driven.
ABD recognizes different driving states, and it
features control strategies adapted to these
states. In situations in which little propulsive power
is required, such as when the vehicle moves off on
a level gravel surface, traction control already
becomes active at low engine speeds. If a large
amount of propulsive power is required, e.g. when
driving off on an uphill slope or for rapid
acceleration, the ABD system is adapted
accordingly.
Anti-slip control (ASR)
The anti-slip control system prevents the wheels
from spinning by adjusting the engine power,
thereby ensuring good lane-holding ability and
stable handling.
Engine drag torque control (MSR)
In conditions of excessive slip, the engine drag
torque control system prevents all driven wheels
from locking up when the vehicle is overrunning.
This is also the case for downshifts on a slippery
road.
Switching off PSM
PSM can be switched off in 2 stages:
– Stage 1 ESC OFF:
Switch off Electronic Stability Control (ESC).
– Stage 2 ESC+TC OFF:
Also switch off Traction Control (TC).
No Brake Control in
h
WARNING
Switch-Off Stages
There is no stabilizing brake control in either of the
switch-off stages (even when the brakes are
used).
f
PSM should always be switched on during
"normal" driving. This particularly applies in
wet conditions.
However, it may be a good idea to switch off PSM
temporarily in exceptional situations:
– On a loose surface and in deep snow.
– When "rocking the vehicle free".