Abstract: An anti-theft system is described adaptable to any motor vehicle having a removable accessory electronic unit such as a high-fidelity stereo component unit installed within a mounting bracket and slidably detachable therefrom. Upon leaving the car, the vehicle owner takes along the entire accessory unit, or alternatively takes only a detachable front control panel from the unit, for secure safekeeping or to be retained in the personal possession of the owner. At the same time, continuity of the electrical circuit supplying current from the storage battery to the motor vehicle fuel pump (or ignition switch, or other control component of the vehicle) is interrupted, thus preventing normal operation of the vehicle and protecting against unauthorized use.