2009 Nissan Xterra Owner's Manual - Page 231

To use the engine block heater: 1. Turn the engine off. 2. Open the hood and unwrap the engine block heater cord. 3. Plug the engine block heater cord into a grounded 3-wire, 3-pronged extension cord. 4. Plug the extension cord into a Ground Fault Interrupt (GFI) protected, grounded 110volt AC (VAC) outlet. 5. The engine block heater must be plugged in for at least 2 - 4 hours, depending on outside temperatures, to properly warm the engine coolant. Use an appropriate timer to turn the engine block heater on. 6. Before starting the engine, unplug and properly store the cord to keep it away from moving parts. Starting and driving 5-39