1996 renault laguna immobiliser?

The central lock button on my 1996 renault laguna doesn't work (open locks) and also the immobiliser light mounted on it is off. It therefore won't start. Nevertheless, there is power to the button. This has led me to believe that there are no signals to or from the control box. Can anyone tell me where the central control box is located? I intend to either change it or disable it....