OBD GMC ENVOY 2009 Owner's Manual

Tire Pressure Light
For vehicles with a tire
pressure light, this light
comes on briey when the
engine is started and
provides information about
tire pressures and the
Tire Pressure Monitoring
System.
When the Light is On Steady
This indicates that one or more of the tires is signicantly
underinated.
A tire pressure message in the Driver Information Center
(DIC), can accompany the light. SeeDIC Warnings and
Messages on page 3-51for more information. Stop and
check the tires as soon as it is safe to do so. If a tire is
underinated, inate to the proper pressure. SeeTires on
page 5-53for more information.
When the Light Flashes First and Then is
On Steady
This indicates that there could be a problem with the
Tire Pressure Monitor System. The light ashes
for about a minute and stays on steady for the remainder
of the ignition cycle. This sequence repeats with
every ignition cycle. SeeTire Pressure Monitor System
on page 5-63for 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 ensures that emissions are at acceptable levels for
the life of the vehicle, helping to produce a cleaner
environment.
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This light should come on
when the ignition is on, but
the engine is not running,
as a check to show it
working. If it does not,
have the vehicle serviced
by your dealer/retailer.
If the check engine light comes on and stays on, while
the engine is running, this indicates that there is an
OBD II problem and service is required.
Malfunctions often are indicated by the system before
any problem is apparent. Being aware of the light
can prevent more serious damage to the vehicle.
This system assists the service technician in correctly
diagnosing any malfunction.Notice:If the vehicle is continually driven with
this light on, after a while, the emission controls
might not work as well, the vehicle’s fuel economy
might not be as good, and the engine might not
run as smoothly. This could lead to costly repairs
that might not be covered by the vehicle warranty.
Notice:Modications made to the engine,
transmission, exhaust, intake, or fuel system of
the vehicle or the replacement of the original tires
with other than those of the same Tire Performance
Criteria (TPC) can affect the vehicle’s emission
controls and can cause this light to come on.
Modications to these systems could lead to
costly repairs not covered by the vehicle warranty.
This could also result in a failure to pass a
required Emission Inspection/Maintenance test.
SeeAccessories and Modifications on page 5-3.
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Make sure to fuel the vehicle with quality fuel.
Poor fuel quality causes the engine not to run
as efficiently as designed and can cause: stalling
after start-up, stalling when the vehicle is changed
into gear, misring, hesitation on acceleration,
or stumbling on acceleration. These conditions
might go away once the engine is warmed up.
If one or more of these conditions occurs, change
the fuel brand used. It will require at least one full
tank of the proper fuel to turn the light off.
SeeGasoline Octane on page 5-5.
If none of the above have made the light turn off, your
dealer/retailer can check the vehicle. The dealer/retailer
has the proper test equipment and diagnostic tools to
x any mechanical or electrical problems that might have
developed.Emissions Inspection and
Maintenance Programs
Some state/provincial and local governments have or
might begin programs to inspect the emission control
equipment on the vehicle. Failure to pass this inspection
could prevent getting a vehicle registration.
Here are some things to know to help the vehicle pass
an inspection:
The vehicle will not pass this inspection if the check
engine light is on with the engine running, or if the
key is in ON/RUN and the light is not on.
The vehicle will not pass this inspection if the
OBD II (on-board diagnostic) system determines
that critical emission control systems have not been
completely diagnosed by the system. The vehicle
would be considered not ready for inspection.
This can happen if the battery has recently been
replaced or if the battery has run down. The
diagnostic system is designed to evaluate critical
emission control systems during normal driving.
This can take several days of routine driving. If this
has been done and the vehicle still does not
pass the inspection for lack of OBD II system
readiness, your dealer/retailer can prepare
the vehicle for inspection.
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