windshield washer fluid pump

I'm unable to get the windshield washer fluid to work on my 2005 Avalanche.  It's topped up and the lines look fine.  Was going to try replacing the fuse but can't seem to find where it's located. The manual doesn't show one. Any thoughts? Thanks.
Duncan

Labelled W/S Wash fuse and relay in the underhood fuse box. If you need a owners manual click the resources button on the left side of every page.

Thanks MS03.  Found it and replaced it.  Works fine now. BTW,  in the manual it says "WS Wash  --  Not used"
Duncan