Everything is going map driven.
The oil level sensor is a pair of electrodes in the pan that measure
voltage between the pair. As the voltage drops, the oil level can be
determined via map based interpolation.
BMW goes from a dumb sensor to a very smart one with sensor failure
detection and you want the old one?
No, it's not.
Perhaps a career change is in order to bring the unenlightened to their
Correct, to a point. It's a capacitance measure, not resistance. Technology
that's been in use on aircraft for fuel contents gauging since Britain
pioneered turbojet passenger aircraft with the De-Havilland Comet.
The other interesting point is that if they fit one in 2 opposite corners
and calibrate the plate areas correctly, the gauge/indicator will always
read true regardless of attitude. Again, this is why aircraft fuel gauges
don't vary with changes in attitude. Modern senders use 2 concentric tubes
as the capacitance plates, the tubes being shaped to vary the distance
between then according to the shape of the tanks at that point, to ensure a
true and accurate reading. Incorporated within the tubes are thermistors
that give either a "wet" or "dry" reading, to control the likes of low level
warnings and fill shut-off valves. The technology ain't new, if I can suss
out the character map I'll post the formula for working out the capacitance,
which demonstrates the plate gaps/areas theory nicely.
Couldn't suss out character map in outlook express, so here goes anyway!
C = Uo Ur A
C = (capacitance, farads)
Uo = relative permeability of air
Ur = relative permeability of any other substance between plates
A = cross-sectional area of plates
d = distance between plates
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