When testing a diode with an ohmmeter, reversing leads yields which result?

• A. Both readings high
• B. Both readings low
• C. One high and one low reading
• D. No reading

Answer: (C)

A diode conducts current in only one direction, so the ohmmeter shows different readings depending on lead orientation. When the leads are placed so the diode is forward-biased, current flows and the meter reads a low resistance. If you reverse the leads, the diode becomes reverse-biased and blocks current, so the meter shows a high resistance (often “OL”). That combination—a low reading in one direction and a high reading in the other—is the expected result for a good diode. If both readings were low, the diode would be shorted; if both were high, the diode would be open or damaged.