GMC 2010 Yukon/Yukon XL Owner's Manual page 261

This indicates that one or more of the tires is
significantly underinflated.
A tire pressure message in the Driver Information
Center (DIC), can accompany the light. See Driver
Information Center (DIC) on page 4 47 for more
information. Stop and check the tires as soon as it
is safe to do so. If underinflated, inflate to the proper
pressure. See Inflation - Tire Pressure on page 6 72
for more information.
For vehicles with a tire
pressure monitoring
system, this light comes
on briefly when the engine
is started. It provides
information about tire
pressures and the Tire
Pressure Monitoring
System.
This indicates that there may be a problem with the Tire
Pressure Monitor System. The light flashes for about a
minute and stays on steady for the remainder of the
ignition cycle. This sequence repeats with every ignition
cycle. See Tire Pressure Monitor Operation on
page 6 75 for more information.
A computer system called OBD II (On-Board
Diagnostics-Second Generation) monitors operation
of the fuel, ignition, and emission control systems.
It ensures that emissions are at acceptable levels for
the life of the vehicle, helping to produce a cleaner
environment.
This light should come on
when the ignition is on,
but the engine is not
running, as a check to
show it is working. If it
does not, have the vehicle
serviced by your dealer.
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