GMC 2005 T-Series Owner's Manual page 96

Malfunction Indicator Lamp
Service Engine Soon Light
First, you will not notice any difference in engine
performance, but your tail pipe emissions may increase.
Second, your engine may not run properly or may
stall without warning. If either of these things happen,
drive or tow your vehicle to your dealer for service.
This light should come on when the ignition is on, but the
engine is not running, as a check to show you it is
working. If it does not come on at all, have it repaired.
Notice: If you keep driving your vehicle with this
light on, after awhile, your emission controls may not
work as well, your fuel economy may not be as good,
and your engine may not run as smoothly. This could
lead to costly repairs that may not be covered by
your warranty.
3-32
If this light comes on or
flashes while you are
driving, two things may
happen.
Oil Pressure Gage
United States
The engine oil pressure gage, on the lower right portion of
your instrument panel cluster, shows engine oil pressure
in psi (pounds per square inch) or in kPa (kilopascals).
Oil pressure may vary with outside temperature and oil
viscosity, but readings of 30 to 40 psi (205 to 275 kPa)
are normal. The normal operating range should be
between 35 and 70 psi (240 to 480 kPa).
A reading in the low pressure zone may be caused by a
dangerously low oil level or other problem. See
Engine Oil on page 5-14 and Scheduled Maintenance
on page 6-5 for more information.
Canada