1997 GMC Suburban Owner's Manual - Page 89

Engine Coolant Heater (Option) In very cold weather, 0°F (- 18O C) or colder, the engine coolant heater can help. To Use the Coolant Heater 1. Turn off the engine. 2. Open the hood and unwrap the electrical cord. 3. Plug it into a normal, grounded 110-volt AC outlet. - /d CAUTION: 1 You'll get easier starting and better fuel economy during engine warm-up. Usually, the coolant heater should be plugged in a minimum of four hours prior to starting your vehicle. 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 intoa properly grounded three-prong 110-volt AC outlet. If the cordwon't reach, use a heavy-duty three-prong extension cord rated for at least 15 amps. 2-15