Chevrolet avalanche 2002 用户手册

The top drain grates are located near the rear glass on
both sides of the vehicle. You may need to clean the
grates and drains if there seems to be blockage. But first
you will have to remove the drain grates by pulling them
off of the vehicle.

To remove each drain grate, do the following:

1. Start with the cargo panels or tonneau cover off. 

See “Cargo Panel Covers” or “Tonneau Cover” 
in the Index for more information.

2. Grasp the edges of the grate and pull it out from the

vehicle. Flush the drain with clean water.