1.Discuss with the customer, patient, user or driver  - do they experience problems that they can describe?
2.Perform preventive maintenance based on age, time since last service, usage time or  driving distance 
3.Perform an inspection according to a standard rutine (predesigned) to discover faults (Inspection of the current state)
4.Complimentary tests are performed (e.g patient: temperature, blood pressure and Exray test)  (computer aided equipment: faultcode readings) Tests easy to perform and worth the money.
5.Perform an analysis and try to find the problem (Fault tree analysis) using input from the patient/customer and your inspection.