GMC 2008 Envoy - Manual (Page 181)

Highbeam On Light
This light comes on when
the high-beam headlamps
are in use.
See Headlamp High/Low-Beam Changer on page 3-8
for more information.
Service Four-Wheel Drive Warning
Light
This light should come on
briefly when you turn on
the ignition, as a check to
show you it is working.
The service four-wheel drive light comes on to indicate
that there may be a problem with the drive system
and service is required. Malfunctions can be indicated
by the system before any problem is apparent,
which may prevent serious damage to the vehicle.
This system is also designed to assist your dealer
in correctly diagnosing a malfunction.
Check Gages Warning Light
The check gages light will
come on briefly when you
are starting the engine.
If the light comes on and stays on while you are
driving, check your coolant temperature and engine
oil pressure gages to see if they are in the warning
zones.
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