The engine heater can provide easier starting and better fuel economy during engine warm-up in 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.

It is shipped from the factory with a tie holding it in place. Use care in removing the tie so that the cord is not damaged.
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.
Warning
Improper use of the heater cord or an extension cord can damage the cord and may result in overheating and fire.
Failure to use the recommended extension cord in good operating condition, or using a damaged heater or extension cord, could make it overheat and cause a fire, property damage, electric shock, and injury.
Keep the cord away from any moving parts.
If you do not it could be damaged.
The length of time the heater should remain plugged in depends on several factors. Ask a dealer in the area where you will be parking the vehicle for the best advice on this.
Starting the Engine
Retained Accessory Power (RAP)Instrument Panel Fuse Block
The instrument panel fuse block is on the underside of the driver side instrument
panel.
Open the fuse panel door by pulling out at the top.
Remove the fuse panel door diagonally.
The vehicle may not be equipped with all of the fuses, relays, and features shown.
...
Managing the Vehicle Damage Repair Process
In the event that the vehicle requires damage repairs, GM recommends that you
take an active role in its repair. If you have a pre-determined repair facility
of choice, take the vehicle there, or have it towed there.
Specify to the facility that any required replacement collision parts be origi ...
What to Use
Warning
Adding only plain water or some other liquid to the cooling system
can be dangerous. Plain water and other liquids, can boil before the proper coolant
mixture will.
The coolant warning system is set for the proper coolant mixture.
With plain water or the wrong mixture, the engine coul ...