Others may be more precise, but in simple terms I would test with ignition off and indicators off including hazard light switch.
What I would do is first set Ohm setting on multimeter and touch the two lead terminal together, the reading you will get will be the same as a dead short, next firmly hold one terminal on a good earthing point then touch the other terminal on the indicator bulb holder's normally live contact, you may get a resistance reading, but you shouldn't see a dead short reading such as you got by holding the two test leads together, repeat test on the other suspect lamp units.
If no joy there then it may be necessary to check deeper into the wiring loom.