The engine coolant heater can provide easier starting and better fuel economy during engine warm-up in cold weather conditions at or below 0°F (−18°C). Vehicles with an engine coolant heater should be plugged in at least four hours before starting.

To Use the Engine Coolant Heater

1. Turn off the engine.

2. Open the hood and unwrap the electrical cord.

On vehicles with the 3.9L V6 engine, the coolant heater cord is located on the driver side of the vehicle, near the strut tower. On vehicles with the 4.6L V8 engine, the cord is located on the driver side of the vehicle on the right side of the engine air cleaner. It is between the engine cover and the engine air cleaner.

WARNING:
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.
If the cord will not reach, use a heavy-duty three-prong extension cord rated for at least 15 amps.

3. Plug the cord into a normal, grounded 110-volt AC outlet.

4. Before starting the engine, be sure to unplug and store the cord as it was before to keep it away from moving engine parts, and prevent damage.

The length of time the heater should remain plugged in depends on several factors. Ask a dealer/retailer in the area where you will be parking the vehicle for the best advice on this.