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

[Hans E. Hansen (FList]

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.

On Tue, Dec 2, 2008 at 4:51 PM, Rick Lindsay <rolindsay [at] yahoo.com> wrote:
> Hello Friends,
>
> As you know, the Mondial was the first of the "modern" V8 Ferraris.  In 
> designing this car the makers included every gadget known to '80s-man.  And 
> of course, some of those doo-dads systematically fail.  The oil level sensor 
> is one of them.  So I ask:
>
> How does the engine oil sensor work?  The "Wiring Diagrams" booklet for the 
> car shows this circuit on Figure 6, item 135.  The sketch shows a two-wire 
> circuit.  Inside, the cartoon shows a coil (or perhaps a resistor) in series 
> with a pair of contacts.  Both wires go to the Monitor Check Control.  That 
> is, neither one is obviously connected to ground or Vcc.  I have made no 
> measurements.  So, in one state, the circuit is "open".  In the other state, 
> the circuit completes through the coil/resistor.  Problem is, I don't know 
> which state reflects proper oil level and which indicates low oil.
>
> And of course, there is another sensor of this kind monitoring the gearbox 
> oil level.  I've never seen that warning light on but the 'low oil' warning 
> light remains on under all oil level conditions.
>
> So your advice is requested.  And yes, I want to repair the circuit, not just 
> learn how to measure one's oil level.
>
> regards,
>
> rick
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