In resistance checks, who is correct: Technician A says the component must be disconnected before checking, Technician B says an infinite reading means the component is shorted?

In resistance checks, it is crucial to disconnect the component from the circuit before performing the measurement. This is because resistance measurements should reflect only the component's own resistance without interference from other components or pathways in the circuit. If the component is still connected, the readings can be misleading, as other components might create parallel paths that affect the ohmic measurement. Therefore, Technician A's statement about disconnecting the component before checking is accurate.

On the other hand, an infinite resistance reading indicates an open circuit within the component, not a short. A short circuit would present a very low resistance reading, not infinite. Therefore, Technician B's interpretation of an infinite reading being indicative of a short is incorrect. Thus, the most accurate statement regarding resistance checks in automotive diagnostics is that only Technician A is correct.