On Tue, 21 May 2019 10:48:22 +0100, Dave Plowman (News) wrote:

I've also no idea on the principle of how it works.

Another curious problem. What have we got?

A 2" sealed probe.
Material?
Is the probe electrically connected to the mounting boss?

Screws horizontally into the sump.
Above/below/at the minimum level?

2 wires.
Is one connected to the probe body and/or mounting boss?
Are the wires open/short circuit or have some resistance?
Does the state change/alter between plenty of oil and not
enough
oil?

Digging about for the "low oil" cut offs for small engines, as I
thought my diesel genset had one and that was just a bare probe so
might lead some where. I found that they are mostly float switches or
pressure operated but there is also an "electro-vibration"
type:

http://outdoorpowerinfo.com/repairs/...l_shutdown.asp
http://outdoorpowerinfo.com/repairs/...oil_shutdown.a
sp

Peizo element mounted in tube, with oil around less vibration, no oil
more vibration, control box to generate appropiate signal. As it's
piezo element one assumes if you took the probe out connected it to a
'scope and gently tapped or vibrated the probe you'd see something on
the 'scope.

--
Cheers
Dave.