Abstract: The present invention discloses a system and method for isolating failures in a locomotive. In the present invention, the cause of failures occurring in the locomotive sub-systems are determined quickly and efficiently, while minimizing the need for human interaction. However, the present invention can incorporate information provided by an operator to produce a more refined diagnosis. In the present invention, incidents are recorded in an incident log and mapped to indicators, which are sent to a fault isolator for diagnosis. The fault isolator uses a diagnostic knowledge base having diagnostic information between failures occurring in locomotive and observable symptoms happening therein. A diagnostic engine then processes the mapped indicators with the diagnostic information in the diagnostic knowledge base and produces a list of the most likely causes for any failures. The present invention then provides a course of action to correct the failures.