2003 Chevrolet Avalanche Owner's Manual - Page 149

After hauling dirt, wood chips, pebbles etc. you will need to flush the midgate drain with water. But first you will have to remove the drain grate by using the following steps: Cargo Area Floor Drains 1. Lower the midgate. See Midgate on page 2-12 in the Index for more information. 2. Pull up on the rear (side opposite the midgate) of the drain grate. Your vehicle also has four cargo-area floor drains located under the cargo mat near the sides of the cargo area. These drains should be cleaned periodically to allow water to exit the cargo area. The cargo mat has cutouts for the drains. You can flush the drains through the cutouts, but if the cargo area is extremely dirty you can lift up the edges of the cargo floor mat or take the whole mat out and flushthe drains with water. 3. Tilt the drain grate away from you and pull it straight out. Reverse the procedure to reinstall the drain grate. 2-76