2009 Chevrolet Silverado 2500 HD Extended Cab Owner's Manual - Page 456

{ CAUTION: Using a match near a battery can cause battery gas to explode. People have been hurt doing this, and some have been blinded. Use a flashlight if you need more light. Be sure the battery has enough water. You do not need to add water to the battery installed in your new vehicle. But if a battery has filler caps, be sure the right amount of fluid is there. If it is low, add water to take care of that first. If you do not, explosive gas could be present. The remote negative (-) terminal is a stud located on the right front passenger side of the engine, where the negative battery cable attaches. See Engine Compartment Overview on page 5-14. Battery fluid contains acid that can burn you. Do not get it on you. If you accidentally get it in your eyes or on your skin, flush the place with water and get medical help immediately. { CAUTION: An electric fan can start up even when the engine is not running and can injure you. Keep hands, clothing and tools away from any underhood electric fan. 5-46