Basic Guidelines on Selection of Test Modes

Having considered the points raised in Identification of the Problem, the following table provide guidelines to help you choose which IFD™ test functions are the best to use in different scenarios.

The precise test functions used are at the complete discretion of the User; however as a 'rule of thumb' it is recommended that Continuity testing is carried out first to confirm that the testing configuration of ITA and UUT has been correctly set up. Then carry out Intermittency testing to isolate any intermittent faults in the UUT. Thereafter, the remainder of the test functions can be used as appropriate to the situation.

Function	Purpose	Practical Application
Intermittence	Detects and isolates random and temporary changes in ohmic characteristics in the circuits of the UUT. The detection result is immediately displayed on the screen.	Immediately detects intermittent faults as they occur. Use of environmental stimulus (especially vibration or gentle tapping of interconnects, particularly in wiring harnesses) is strongly recommended. Can be used for troubleshooting faults of installed and uninstalled components such as wiring harnesses, interconnection components (eg relays, circuit breakers) and chassis interconnects in rack-mount electronic units and Line Replaceable Units
Continuity	Measures and records ohmic continuity readings for all test points in the UUT.	Confirms that the testing configuration of ITA and UUT has been correctly set up - hence it is recommended that this test be carried out first. Not all faults are intermittent so this test rapidly identifies if there are any 'hard' continuity faults. Any faults detected can then be investigated using the other test functions. All continuity results are recorded for each Test Point, so - bearing in mind the standardised and repeatable nature of the test - this provides a useful source of data for future investigations and trend analysis.
Shorts	Detects if any of the test points have short circuit paths to any other known nodal clusters outwith their own designated node. The detection result is immediately displayed on the screen.	Immediately detects Shorts faults as they occur. Use of environmental stimulus (especially vibration or gentle tapping of interconnects, particularly in wiring harnesses) is strongly recommended. Can be used for troubleshooting faults of installed and uninstalled components such as wiring harnesses, interconnection components (eg relays, circuit breakers) and chassis interconnects in rack-mount electronic units and Line Replaceable Units
Trace	After a nodal shorting condition is found using Shorts testing, Trace isolates the exact circuit which is shorting to the failing node, where one node is shorted to some other node.	Trace is used in combination with Shorts - once a short has been detected then Trace can be used to isolate the affected test point.
LogScope™	Detects and graphically tracks small resistance changes measured across any two test points in the UUT. The detection result is immediately displayed on the screen.	This would typically be carried out if a test point has exhibited intermittent faults and/or is showing as an anomaly in other tests. LogScope is very useful for identifying and quantifying noisy and unstable test points in the UUT. The test can be run while the User varies the amount of manual manipulation or environmental stimulus to the UUT to see which conditions have the greatest effect on the test point. Screen shots can be captured automatically for subsequent analysis and comparison purposes.
SSTDR	Detects and graphically outputs distance to a state, either Open/Closed along a pair of cables within a harness. The detection result is immediately displayed on the screen.	This would typically be carried out if a pair of test points, normally twisted pair or coaxial needs to be measured and/or characterised, and, if available, compared to a 'gold'. Screen shots can be captured automatically for subsequent analysis and comparison purposes.
Tracker	Detects and graphically outputs an LCR charateristic across components in a circuit. The detection result is immediately displayed on the screen.	This would typically be carried out across a component in a circuit, ie a diode, inductor etc needs to be characterised, and, if available, compared to a 'gold'. Screen shots can be captured automatically for subsequent analysis and comparison purposes.

Basic Guidelines on Selection of Test Modes

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