14. The diagnostic system of claim 12 further comprising a means for determining the temporal order of signals indicative of first and second independent engine faults and for establishing an order of the testing thereof in dependence thereon.
12. The diagnostic system of claim 1 wherein said knowledge database means further comprises a means for determining which of said engine fault signals are indicative of independent and dependent type of engine faults and comprising a means for establishing an order of the testing thereof in dependence on said determination.