GMC T-Series 2007 Owner's Manual page 72

During this warm-up period, check your warning
lights and gages:
•
If oil pressure does not begin to rise within
15 seconds of starting, stop the engine and find
the cause. See Oil Pressure Gage on page 130
for more information.
•
If the engine coolant temperature gage needle
goes into the hot area on the gage, stop the
engine and find the cause of the overheating.
See Engine Coolant Temperature Gage on
page 128 for more information.
•
If you have air brakes, the dual-needle air
pressure gage should read at least 115 psi
(790 kPa) for both service systems before you
try to move the vehicle. When air pressure is
below 60 psi (420 kPa), the LOW AIR light will
come on and you will hear a tone alarm. See
Brake System Warning Light on page 124 for
more information. If the pressure does not build
up or drops during warm-up, stop the engine
and find the cause before you try to move the
vehicle. Recommended air pressure before
driving is 120 psi (830 kPa). See Air Pressure
Gage on page 136 for more information.
72
•
The charging system light should come on
when the ignition key is turned to ON or START
and should go out when the engine is running
above idle. If the light does not go out or comes
back on during normal engine operation, have
the charging system checked right away.
(This light tells you if the generator is not
charging; it does not reflect the condition of
the battery.) See Charging System Light on
page 122 for more information.
•
The voltmeter charge indicator gage tells you
the condition of your battery's charge. The gage
should be in the center area during engine
operation. The red area on the left indicates an
undercharge condition; the red area on the right
indicates an overcharge. If the gage is in either
red area, have the battery and charging system
checked right away. See Voltmeter Gage on
page 122 for more information.
Notice: Do not allow the engine to operate at
low idle for more than five minutes. This can
cause low engine operating temperatures which
can affect engine operation and reduce engine
life. Engine idle speed should be increased to
1200 rpm whenever extended idle is required.