A resistance reading describes everything the meter can see, which is usually more than the component you are pointing at.
In-circuit readings mislead constantly. The number is real; what it is a number for is not what you assumed.
Put probes on a component still wired into a board and the meter reads the component in parallel with every other path between those two points. The result is lower than the component alone and it is not wrong -- it is the right answer to a question about the whole network. Lift the component out and you get the answer you actually wanted.
Check yourself: A resistor reads lower in the board than it does on the bench. Which reading is faulty?
Answer: Neither. A component measured in-circuit can read differently than an isolated component.
In-circuit, the meter measures the component in parallel with everything else connected across it. Both readings are correct measurements of different things.
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Written from the owner's poster for this lesson. Nothing added beyond what the poster states.
Written for Texas apprentices as free study material. The Texas apprentice licence is an application, not an exam (Occupations Code 1305.161), and nothing here counts as apprenticeship hours or continuing-education credit. VoltMark is not affiliated with, endorsed by, or sponsored by NFPA, PSI, TDLR, or any state or local licensing authority. Always follow your employer's safety programme and your supervising electrician.
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