Circuit for automatic shut-down of electronically controlled diesel engine

An internal combustion engine comprising:

• an ignition switch that is selectively operated on and off respectively to respectively connect and disconnect electric current from an electric power source to and from circuitry associated with the engine,
• a fuel shut-off solenoid valve that is selectively operable to open and close a fuel supply to the engine, said fuel shut-off solenoid valve being closed and open respectively by the absence and presence respectively of energizing current to it,
• an electronic engine control module for exercising control over certain engine functions including control of said fuel shut-off solenoid valve by commanding said energizing current to be supplied to said fuel shut-off solenoid valve via a current path between said electronic engine control module and said fuel shut-off solenoid valve, said electronic engine control module having a diagnostic mode, operative with the engine not running but with the ignition switch on, requiring continuity of said current path to said solenoid valve;
• and
• an engine shut-down circuit operative with the engine running and the ignition switch on but functioning separately from said electronic engine control module for shutting the engine down upon the occurrence of one or more conditions indicative of a need to stop the engine for the purpose of avoiding permanent damage thereto, said shut-down circuit including:
• one or more detection sensors for detecting the occurrence of said one or more conditions,
• switch means interposed in said current path between said electronic control module and said fuel shut-off solenoid valve,
• an electrical connection between said ignition switch and an operating means associated with said switch means,
• shut-down switch means effective when said ignition switch is on and the engine is running to cause said switch means to maintain said current path closed prior to said one or more detection sensors detecting said one or more conditions, said shut-down switch means effective upon said one or more detection sensors detecting said one or more conditions to cause said switch means to open said current path, thereby interrupting said energizing current and causing said fuel shut-off solenoid valve to close and shut off fuel to the engine;
• and
• means causing said switch means to be closed when the engine is not running and said ignition switch is on.