2003 Chevrolet Avalanche Owner's Manual - Page 359

Checking Coolant The coolant surge tank is located in the engine compartment on the passenger's side of the vehicle. Turning the surge tank pressure cap when the engine and radiator are hot can allow steam and scalding liquids to blow out and burn you badly. Never turn the surge tank pressure cap - even a little - when the engine and radiator are hot. The vehicle must be on a level surface. When your engine is cold, the coolant level should be at the FULL COLD mark. If the LOW COOLANT LEVEL message comes on and stays on, it means you're low on engine coolant. See Engine Compartment Overview on page 5-12 for more information on location. See "Low Coolant Level" under DIC Warnings and Messages on page 3-56. Adding Coolant If you need more coolant, add the proper DEX-COOL@ coolant mixture at the surge tank, but only when the engine is cool. 5-26