GMC 2013 Sierra Denali Owner's Manual page 275

When the transfer case is in 4LO,
the stability system is automatically
disabled, the StabiliTrak light comes
on, and the appropriate message
will appear on the DIC. Both traction
control and StabiliTrak are
automatically disabled in this
condition.
The TCS is part of the StabiliTrak
system. Traction control limits wheel
spin by reducing engine power to
the wheels (engine speed
management) and by applying
brakes to each individual wheel
(brake-traction control) as
necessary.
The TCS is enabled automatically
when the vehicle is started. It will
activate and the StabiliTrak light will
flash if it senses that any of the
wheels are spinning or beginning to
lose traction while driving. If traction
control is turned off, only the
brake-traction control portion of
traction control will work. The
engine speed management will be
disabled. In this mode, engine
power is not reduced automatically
and the driven wheels can spin
more freely. This can cause the
brake-traction control to activate
constantly.
The TCS may activate on dry or
rough roads or under conditions
such as heavy acceleration while
turning or abrupt upshifts/downshifts
of the transmission. When this
happens, a reduction in acceleration
may be noticed, or a noise or
vibration may be heard. This is
normal.
If cruise control is being used when
the system activates, the StabiliTrak
light will flash and cruise control will
automatically disengage. Cruise
control may be reengaged when
road conditions allow. See
.
StabiliTrak may also turn off
automatically if it determines that a
problem exists with the system.
If the problem does not clear itself
after restarting the vehicle, see your
dealer for service.
Vehicles with StabiliTrak have a
Trailer Sway Control (TSC) feature.
See
.
Vehicles with StabiliTrak have a Hill
Start Assist (HSA) feature. See
Adding non-dealer accessories can
affect the vehicle's performance.
See
.
.