Turn off power to the circuit
Set the multimeter to diode test mode
Place the red probe on the anode
Place the black probe on the cathode
Read the forward voltage drop on the display
Reverse the probes
Check for OL or no conduction in reverse direction
If both directions show conduction, the diode may be shorted
If both directions show OL, the diode may be open
Remove the diode from the circuit if the reading is unclear
Compare the reading with the diode’s expected forward voltage range