Ferrari Mailing List: Re: Mondial owners - electro-technical question

[Hans E. Hansen (hans]

Oh, PS:

Just thought of something.  In #2 below, perhaps there is supposed
to be something akin to a thermistor or somesuch between the prongs
of the sensor.  If so, it may work sort of like the mass air flow sensor
in the intake of many injection system.  A current is passed thru and
any heat sink effect from being submerged could alter the resistance
charisteristics of the circuit.  This may be what you are seeing on the
schmatic.  Or else the resistor on the schmatic is representing the
oil itself.

Hans.

On Tue, Dec 2, 2008 at 5:12 PM, Hans E. Hansen <FList [at] hanshansen.org> 
wrote:
> OK, I don't know any of this for certain, but I've heard comments from a
> few owners.
>
> Way, way back, I saw a photo of the sensor.  It had 2 prongs, as I recall.
> I *think* that the 2 prongs simply were submerged in the oil at the proper
> level.  Altho oil is likely an insulator (hmmm.....  never measured it, tho),
> there may be some very high level of resistance that the circuit is measuring.
> ie - open circuit -> no oil.  100Mohm -> proper oil.
>
> What sort of dovetails with this is that I have also seen the prongs bent
> together (thus shorting them out) to get the idiot light to go off.
>
> For whatever reason, it seems many of these don't work.  Could be:
> 1.  The circuit is designed right on the edge and any slight miscalibration
> (or even different motor oil) makes it read goofy (technical term)  This could
> be the case if the circuit was trying to tell the difference between 100Mohm
> and open, for example.
> 2.  The prongs of the sensor maybe had something between them that
> falls off, or maybe they had some special coating that goes away in time.
> 3.  The black box circuit itself isn't very robust and fails.
> 4.  You need to fill the crankcase with olive oil.
>
> Hans.
>