At which step in a funneling analysis troubleshooting procedure are tests generally limited to a single unit in the system block diagram?

• A. Level 1
• B. Level 2
• C. Level 3
• D. Level 4

Answer: (C)

In this funneling approach, you progressively narrow the focus from the whole system down to individual components. At the early stage you assess overall behavior and how the major blocks interact. When you move to checking interfaces between blocks, you’re still looking across more than one unit to see if signals and control paths are carrying correctly. The step where tests are limited to a single unit in the system block diagram is the point where you isolate that one component and test it by itself. By removing the influence of other units, you can see if the unit under test behaves as expected, which helps confirm whether the fault lies there or elsewhere. If that unit passes isolated testing, you know to look at other parts; if it fails, you have strong evidence the unit is faulty and should be addressed.