The Diagnostic Knowledge Base contains a diagnostic model of the item that is generated from design data. The model is in the form of a connectivity matrix that represents the propagation of faults (rows in the matrix) to observable measurement locations and the coverage of tests that Pass or Fail (columns in the matrix).  When used in run-time, the software algorithms correlate test results to the model to dynamically derive a fault isolation call-out.      

The model-based diagnostic software object is used in lieu of programmed fault trees. In run-time, the Diagnostician provides dynamic fault isolation without complex diagnostic logic paths, by reading test/sensor results. The diagnostic logic is not "fixed" to a pre-determined, static diagnostic tree, but rather is dynamic. The Diagnostician dynamically interprets test results that can come from any source, in any order, and with as many or as few test results at a time as the test source can provide.  Static test trees, on the other hand, are based upon one test result at a time, in a pre-determined sequence, and from a fixed test source.