The cruise control on my 94 318is didn't work when I bought it recently. So I did a bunch of reading on severfal forums to see what others did to trouble shoot the problem. I eliminated the "brain" by replacing it with another used one from a car with a working CC. It still didn't work. Then I read that it may be the clutch switch. I got under the dash and immediately saw that the switch (white in color) was stuck in the compressed position. I then went to my parts cars and removed the switch from it. This helped me understand exactly how to remove it, which was a bit ticky (a screwdriver and pliers). Then I used my electrical testor to check the continuity of that switch to make sure it was working properly. It was. Then I removed the switch from my 94 and swapped it out. The problem was resolved. My cruise is now working and it didn't cost anything.
If your CC doesn't work, start your trouble-shooting search here were it is the easiest to eliminate. You can even check the continuity of the switch without removing it, to see if in fact your problem is just your switch. Simply unhook the connector at the switch so you can access the two contacts (one positive and the other negative) with an electrical testor to check the continuity. That will tell the story of whether it is working properly in the compressed and uncompressed positions. If you discover that this is your problem and you aren't fortunate to have another switch available, these switches sell for about $13 at aftermarket places on the internet.