First UNPLUG YOUR VESSEL FROM AC POWER !! With the AC power to the vessel OFF disconnect both green wires from the GI and connect your DVM leads to the studs.


If the diodes are working you should see a reading of .8 to 1.0. here the reading is .973..


If the diodes are bad you will not get a reading or will get the OL message (open leads) if using a Fluke. Older style galvanic isolators like this fail "open"...