The D192C, when faulted, is not creating a short between common and supervised zone when testing with a multi-meter.
Test using voltage, not Ohms.
In order to test this properly, place the multi-meter on DC voltage and the meter leads accross terminal 2 and 3 on the D192C or G card. Create a trouble on the card (place the disconnect switch to the silence mode). Use the voltage ranges that are labled on the panel's metal cover.
NOTE: The D192C or G card only needs one panel common and there should also be a 1K resistor accross terminal 2 and 3 (common and supervised zone).
OPEN: 3.7-5.0 VDC
NORMAL: 2.0-3.0 VDC
SHORT: 0.0-1.3 VDC
Part numbers D192C, D192G