2009 Hummer H3T Owner's Manual - Page 85

Features and Controls 2-19 Engine Coolant Heater 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. An internal thermostat in the plug-end of the cord may exist which will prevent engine coolant heater operation at temperatures above 0°F (−18°C). { CAUTION 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. 4. Before starting the engine, be sure to unplug and store the cord to 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. Automatic Transmission Operation To Use the Engine Coolant Heater 1. Turn off the engine. 2. Open the hood and unwrap the electrical cord. The cord is located in the engine compartment behind the underhood fuse block on the driver side of the vehicle. 3. Plug it into a normal, grounded 110-volt AC outlet. The automatic transmission has a shift lever on the console.