Overheated Engine Protection Operating Mode; Engine Fan Noise; Power Steering Fluid - GMC Sierra Denali 2009 Owner's Manual

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Overheated Engine Protection
Operating Mode
If an overheated engine condition exists and the
ENGINE POWER IS REDUCED message is displayed,
an overheat protection mode which alternates firing
groups of cylinders helps prevent engine damage. In this
mode, you will notice a loss in power and engine
performance. This operating mode allows the vehicle to
be driven to a safe place in an emergency. Driving
extended miles (km) and/or towing a trailer in the
overheat protection mode should be avoided.
Notice: After driving in the overheated engine
protection operating mode, to avoid engine damage,
allow the engine to cool before attempting any
repair. The engine oil will be severely degraded.
Repair the cause of coolant loss, change the oil and
reset the oil life system. See Engine Oil on
page 5-15.

Engine Fan Noise

The vehicle has electric cooling fans. You might hear
the fans spinning at low speed during most everyday
driving. The fans can turn off if no cooling is required.
Under heavy vehicle loading, trailer towing, and/or
high outside temperatures, or if you are operating the
air conditioning system, the fans can change to
high speed and you might hear an increase in fan noise.
This is normal and indicates that the cooling system
is functioning properly. The fans change to low speed
when additional cooling is no longer required.

Power Steering Fluid

See Engine Compartment
Overview on page 5-14 for
reservoir location.
5-35

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