GMC 2009 Sierra - Manual (Page 180)

Tire Pressure Light
This light comes on briefly
when the engine is started.
This light will also come on when one or more of your
tires are significantly underinflated.
A tire pressure message in the Driver Information Center
(DIC), may accompany the light. See DIC Warnings and
Messages on page 3-59 for more information.
Stop and check your tires as soon as it is safe to
do so. If underinflated, inflate to the proper pressure.
See Tires on page 5-58 for more information.
If a problem is detected with the Tire Pressure Monitor
System, this light will flash for approximately
60 seconds and then stay on solid for the remainder of
the ignition cycle. See Tire Pressure Monitor System
on page 5-66 for more information.
Malfunction Indicator Lamp
Check Engine Light
A computer system called OBD II (On-Board
Diagnostics-Second Generation) monitors operation of
the fuel, ignition, and emission control systems. It makes
sure that emissions are at acceptable levels for the
life of the vehicle, helping to produce a cleaner
environment.
The check engine light
comes on to indicate
that there is an OBD II
problem and service
is required.
Malfunctions often are indicated by the system before
any problem is apparent. This can prevent more serious
damage to your vehicle. This system is also designed
to assist your service technician in correctly diagnosing
any malfunction.
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