Diagnostic system in an engine management system

A diagnostic system in an engine management system for generating a diagnostic trouble code (DTC) to indicate the operational status of a component or sub-system which is being evaluated by said diagnostic system, said diagnostic system comprising:

• a diagnostic function module (DF module) for each DTC or a group of related DTCS, said DF module including means for executing an evaluation routine to evaluate the operational status of a component or sub-system to which the DTC of the specific DF module relates, and
• a dynamic scheduler for determining which evaluation routine associated with said DF module may be allowed to execute at a particular time;
• wherein each said DF module comprises means for determining the priority with which the evaluation routine associated with that DF module should be executed;
• wherein said dynamic scheduler comprises means, responsive to signals from engine control functions and DF modules, for preventing other execution of engine control functions or evaluations by DF modules if the other engine control functions or the evaluations by DF modules interfere with a currently-performance control function or a currently performed evaluation by a DF module.

A diagnostic system in an engine management system for generating a diagnostic trouble code (DTC) to indicate the operational status of a component or sub-system which is being evaluated by said diagnostic system, said diagnostic system comprising:

• a diagnostic function module (DF module) for each DTC or a group of related DTCs, said DF module including means for executing an evaluation routine to evaluate the operational status of a component or sub-system to which the DTC of the specific DF module relates, and
• a dynamic scheduler for determining which evaluation routing associated with said DF module may be allowed to execute at a particular time;
• wherein each DF module comprises means for determining the priority with which the evaluation routine associated with that DF module should be executed;
• wherein said DF module further comprises means for comparing said evaluated data with previously generated data relating to evaluations of the component or sub-system to which the DTC of the specific DF module relates and, in the event that an evaluated fault signal is generated, for comparing said signal with subsequently produced evaluated data to thereby generate either a controlled fault signal or a controlled no-fault signal.