no brake lights

I've read many peoples probs the same as my own; 1998 1500 w/ no brake lights. Checked the in-cab fuse. Then looked under the hood and found the "brake light relay". What does this do and could it be the problem? I'm going out to try the cruise control test for the switch on the brake pedal. If this turns out to be the prob, exactly how do I get the switch off. I can barely get my hand up there just to touch the thing, let alone to take it out. Thanks DAL