1. A method for troubleshooting a fault to determine a root cause of the fault, the method comprising: using a computer to create a Bayesian network model based on information obtained from a Fault Isolation Manual (FIM), where said FIM provides tests to be performed in troubleshooting said fault to determine a root cause of said fault; using heuristics to determine a structure and conditional probabilities for the Bayesian network; imputing a plurality of test costs to the computer which are inherent in the FIM by first generating a plurality of constraints between the cost of each test and fault probabilities that hold for all fault scenarios; using a linear programming algorithm running on the computer to solve said plurality of constraints, and to construct a tuned Bayesian network model; causing the computer to use the tuned Bayesian network model to compute, at each operation of the troubleshooting process: a first set of information including a ranked list of possible component faults along with a probability associated with each one of said possible component faults, according to probabilities given accumulating test evidence, and a second set of information including a prioritized list of troubleshooting tests, along with a test value for each one of said troubleshooting tests, with the prioritized list of said trouble shooting tests being ranked according to their test value; and using the computer to simultaneously display on a display system, at each operation of the troubleshooting process: the ranked list of possible component faults along with the probability associated with each one of said possible component faults; said prioritized list of troubleshooting tests being in an ordered list on the display; the test value determined for each one of said troubleshooting tests being displayed adjacent its associated one of the troubleshooting tests; and wherein each said test value further comprises a sum of information entropy, if a specific test outcome is known, and a test cost of a specific one of said tests.