Hi everyone I am Grizzly and new to the forum

I have a 1999 Chevy Z71 4w drive with an electrical short somewhere ...
I have taken the neg cable loose and light tester show's an electrical draw. .
Under the hood under the Fuse box moved it and unplugged everything around it and it still has a draw ... The test light will be bright and then flicker a little bit and then go dim for a few seconds and then go back bright .. does that randomly ..
Need some ideas for this problem
Thanks for any help

Grizzly