Engine Checks Before Operating - GMC T-Series 2007 Owner's Manual

On vehicles equipped with a diesel engine
exhaust brake, the exhaust brake switch must
be on. See Diesel Engine Exhaust Brake on
page 74 for more information. The indicator in the
exhaust brake switch will be lit when the exhaust
restrictor is active. The exhaust brake indicator
light in the center of the instrument panel will also
be lit whenever the exhaust restrictor is active.
See Exhaust Brake Indicator Light on page 133 for
more information.
When the engine coolant temperature is below
149°F (65°C) and the outside temperature is below
50°F (10°C), the exhaust restrictor will come on
within 60 seconds of starting the engine. After
running the engine for an additional 10 seconds,
the engine idle will increase.
The exhaust restrictor will shut off and engine idle
will return to normal once the engine is warmed
up, or the brake pedal is pressed.

Engine Checks Before Operating

When you have started your engine, let it run for
20 to 30 seconds before you put a load on the
engine. But do not leave the vehicle while
the engine is running.
Avoid unnecessary idling of diesel engine
equipped vehicles.
If the engine idles too long, the temperature of the
engine coolant will fall below the normal operating
range. Low engine operating temperature causes
several conditions which affect engine operation
and reduce engine life.
The engine should be permitted to go through a
warm-up period. Operate the vehicle at a minimum
of 600 rpm during the warm-up period. During
this period and during operation, the following
observations should be made.
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