GMC Hummer H3 2008 Owner's Handbook Manual page 306

The engine coolant temperature
gauge shows the engine coolant
temperature. If the pointer reaches
the shaded warning area of the
gauge, the engine is too hot!
An overheat warning message
may appear in the driver informa-
tion centre display.
See "Driver Information Centre
Messages" in Section 1 for more
information.
To avoid added strain on a hot
engine, the air conditioning
compressor is automatically
turned off.
If you see or hear steam coming
from the engine, stop and turn the
engine off. Do not open the
bonnet until the engine has cooled
down.
If you get the overheat warning
with no sign of steam:
1. Turn off your air conditioner
and turn on the heater at high
speed.
2. In heavy traffic, shift to
N (Neutral) while stopped.
Pull over and stop the vehicle
as soon as it is safe to do so.
Allow the engine to idle for a
few minutes.
If the coolant temperature gauge
still shows an overheated condi-
tion, pull over, stop and park your
vehicle right away.
If there is still no sign of steam,
press the accelerator pedal until
the engine speed is about twice as
fast as normal idle speed for about
3 minutes while you are parked.
Section 5
If the overheat warning continues,
turn off the engine and get every-
one out of the vehicle right away.
If the coolant in the coolant tank
has been boiling, do not touch it
until it has cooled down.
The vehicle should be parked on a
level surface.
The level in the coolant recovery
tank should be at or above the
FULL COLD mark.
If the coolant level is low, there
may be a leak in the cooling
system.
CAUTION
Engine parts may be very hot.
Do not touch them.
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