Again, just like with the diode test function on the DVM you'll need to reverse the leads to check the flow in the opposite direction. The bulb should light.


Galvanic isolators are in the path of the safety ground for your vessel so it is critical that you know your GI is working. Newer GI's have either idiot lights that tell you it is on or are fail safe so there is much less need to worry about losing the safety ground.


This test is for older style GI's like the one pictured. There are still perhaps hundreds of thousands of boats with this style GI installed on them.





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