GMC Sierra Denali 2017 Owner's Manual page 264

cold weather conditions at or below
18 °C (0 °F). Vehicles with an
engine heater should be plugged in
at least four hours before starting.
An internal thermostat in the
plug-end of the cord may exist,
which will prevent engine coolant
heater operation at temperatures
above 18 °C (0 °F).
If the vehicle has a diesel engine,
see the Duramax diesel
supplement.
To Use the Engine Coolant
Heater
1. Turn off the engine.
2. Open the hood and unwrap the
electrical cord. The cord is
secured to the driver side
fender with a clip, next to the
engine compartment fuse
block. Carefully remove the
wire tie that bundles the
electrical plug. Do not cut the
electrical cord.
Check the heater cord for
damage. If it is damaged, do
not use it. See your dealer for
a replacement. Inspect the
cord for damage yearly.
3. Plug the cord into a normal,
grounded 110-volt AC outlet.
Warning
Improper use of the heater cord
or an extension cord can damage
the cord and may result in
overheating and fire.
Plug the cord into a
three-prong electrical utility
receptacle that is protected
by a ground fault detection
function. An ungrounded
outlet could cause an
electric shock.
Use a weatherproof,
heavy-duty, 15 amp-rated
extension cord if needed.
Failure to use the
recommended extension
cord in good operating
(Continued)
Driving and Operating
Warning (Continued)
condition, or using a
damaged heater or
extension cord, could make
it overheat and cause a fire,
property damage, electric
shock, and injury.
Do not operate the vehicle
with the heater cord
permanently attached to the
vehicle. Possible heater
cord and thermostat
damage could occur.
While in use, do not let the
heater cord touch vehicle
parts or sharp edges. Never
close the hood on the
heater cord.
Before starting the vehicle,
unplug the cord, reattach
the cover to the plug, and
securely fasten the cord.
Keep the cord away from
any moving parts.
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