Lutron Electronics DM-9962SD Operation Manual page 16

b. When connected as shown in Fig. 3, a reverse check on
the diode is made. If the diode under test is good, "––––"
will be displayed. If the diode under test is defective,
" 0.000 " or other numbers will be displayed. Proper diode
testing should include both steps a. and b. above.
Fig. 2
Fig.2
Fig. 3
Fig.3
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