1996 Buick Riviera

We have a 1996 buick riviera, 70,103 miles on the car. We are have a problem with the cruise control, the trip domitor, and the tracktion control.
The cruise controle will not come on after the car is stated, it will come on for a few mins but then go out, I do understand that there can be more then one problem with it but I am not sure what to look for first.
The trip dometor will not turn to 0 at all nothing happens when we push the buttom, do you think it is in the dashboard, and the tracktion controle is right under the trip domitor butten.
I hope you can help me. If not can you tell me where I can get a book to help me out.

Thank you

P.S. A friend said that he check out the code tester and a code come up as braksw low voilit, if you can tell me what that is.