GMC 2003 GMT560 T-Series, Owner'S Manual, Page: 49 / 284

Notice: For diesel engines, don’t 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.
Once started, the engine should be placed under
load to allow the engine coolant temperature
to reach 150°F (66°C) before shutting off the engine.
Engine Coolant Heater
In very cold weather, 0°F (
−
18°C) or colder, the engine
coolant heater can help. You’ll get easier starting
and better fuel economy during engine warm-up.
Usually, the coolant heater should be plugged in a
minimum of four hours prior to starting your vehicle.
To Use the Engine Coolant Heater
1. Turn off the engine.
2. Find the plug-in receptacle (either behind the front
bumper or in the component box).
3. Plug a heavy-duty, three-prong extension cord
(rated for at least 15 amps) into the vehicle’s
plug-in receptacle first. Then plug the extension
cord into a normal, grounded 110-volt AC outlet.
{
CAUTION:
Plugging the cord into an ungrounded outlet
could cause an electrical shock. Also, the
wrong kind of extension cord could overheat
and cause a fire. You could be seriously
injured. Plug the cord into a properly grounded
three-prong 110-volt AC outlet. Use a
heavy-duty three-prong extension cord rated
for at least 15 amps.
4. Before starting the engine, be sure to unplug
the cord.
How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature.
From 32°F to
−
10° F (0°C to
−
23°C), keep the coolant
heater plugged in at least two hours. Below
−
10°F
(
−
23°C), keep the coolant heater plugged in for
a minimum of eight hours or overnight. It will not harm
either the coolant heater or the vehicle to leave the
coolant heater plugged in longer than the times stated.
Be sure to remove and store the cord before starting
the engine. See
What Fuel to Use on page 5-5 for
information on what fuel to use in cold weather.
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