How do I test an extension cord for shorts and ground faults with a multimeter?

Set your multimeter to resistance or continuity mode. With the cord unplugged, test hot to neutral, hot to ground, and neutral to ground — all should read infinite resistance (OL) if the cord is good. Then check each plug pin to the corresponding socket pin for near-zero resistance to confirm continuity. If any unexpected connection shows continuity or an expected path is open, toss the cord.