GMC TopKick 2007, Owner'S Manual, Page: 212 / 430

Traction Control System (TCS)
Your vehicle may have a traction control system
that limits wheel spin. This is especially useful
in slippery road conditions. The system operates
only if it senses that one or both of the rear wheels
are spinning or beginning to lose traction. When
this happens, the system applies the brake(s)
at the affected wheel(s).
The bottom light on the TCS on/off button will
come on when the TCS is limiting wheel spin.
You may feel or hear the system working, but this
is normal. The TCS will function at speeds up
to about 25 mph (42 km/h).
The TCS may operate on dry roads under some
conditions. When this happens, you may notice a
reduction in acceleration. This is normal and
doesn’t mean there’s a problem with your vehicle.
Examples of these conditions include a hard
acceleration in a turn, an abrupt upshift or
downshift of the transmission or driving on
rough roads.
When the light in the top of the TCS button is on,
the TCS is off and will not limit wheel spin.
Adjust your driving accordingly.
The light in the top of the TCS button will come on
if the TCS is turned off by pressing the TCS
on/off button.
The light may also come on if a problem has been
detected in either the traction control system or
the anti-lock brake system.
The traction control system automatically comes
on whenever you start your vehicle. To limit wheel
spin, especially in slippery road conditions, you
should always leave the system on. But you
can turn the traction control system off if you ever
need to. You should turn the system off if your
vehicle ever gets stuck in sand, mud or snow and
rocking the vehicle is required. See
Rocking
Your Vehicle to Get It Out on page 232 for more
information.
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