This seemed like a fairly simple issue to me, but...

I want to test the windshield washer fluid level switch from my 86 300SDL. I have the switch out of the tank. It has two connections on top. When you turn it upside down, there is a clunk. I know from disassembling one that there is a float inside. I assumed that when the float drops to the bottom, there should be connectivity across the two connectors at the top, and when the float floated up, the connectivity was broken.

I now have another used switch. Both my disassembled one and my "new" used one never show connectivity, whether right-side up or up-side down.

Do I now have two failed switches? Or do I not understand how these work? Help appreciated.


Just for fun, I have attached a photo of the disassembled switch. From left to right, the parts are 1) bottom plate, 2) fluid drain regulator, 3) float, 4) switch body.

The float has what appears to be a ferrous-magnetic ring at the top which I assume causes the electrical field change necessary to signal low fluid level. The "fluid drain regulator" (my terminology) has a small circuitous channel to slow the fluid drain rate from the switch, much like what you find in the bottom of the fuel sender unit.

Attached Thumbnails

 

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Mike Frederick
1986 300SDL, 240K+ miles
1985 300D KaliKar, 270K+ miles