First I would check for the third brake lamp, that is the only one that would interfere with cruise operation.
Then I would unplug the cruise control module and us a test lamp to check for power and ground, and for power when you hit all of the switch positions. If you have good powers, and ground to the module then the cruise module is bad. If you find that part of the switch is not sending power to the module then there is your problem.
You can short out the airbag coil if you try hard, it is not as easy as some think. If you need wiring info I will do my best to get it to you.