GMC 1993 Jimmy Owner's Manual page 79

In very cold weather, 0°F (-18°C) or colder, the optional engine block heater
can help. You'll get easier starting and better fuel economy during engine
warm-up.
To use the block heater:
1. Turn off the engine.
2. Open the hood and unwrap the electrical cord.
3. Plug it into a normal, grounded 110-volt outlet.
Plugging
the
cord
into
an
ungrounded
outlet
could
cause an elec&ai
A
shack. Also, the wrong kind of extension cord could overheat
and
muse a
fire. You could be seriously injured. Plug the
cord
into a
properly
grounded
three-prong 110-vott
outlet.
If the cord won't reach,
use a heavy-duty three-prong extension cord rated fur at teast 15
amps.
I
NOTICE
How long should you keep the block heater plugged in? The answer depends
on the weather, the kind of oil you have, and some other things. Instead of
trying to list everything here, we ask that you contact a General Motors
dealer in the area where you'll be parking your vehicle. The dealer can give
you the best advice for that particular area.
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