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

[Hans E. Hansen (FList]

I guess I should also mention that: a) the photos I saw were from a
3.2.  Don't know if they are different, and b) I never saw any
correspondence from anybody that ever fixed one.  They simply
bent the contacts.  I don't know if they did this because it was
easy or it was the only practical method because the needed
parts were unobtanium.

Hans.

On Tue, Dec 2, 2008 at 5:39 PM,  <rolindsay [at] yahoo.com> wrote:
> Thanks Hans. Reading further in the service manual, the circuit supplies 5v 
> to the detector and is only suppose to read for the first few seconds of 
> power-up (when car is level).   Could be measuring resistance.
>
> If the light remains on at all times, then something is way wrong. I'll find 
> that wrong. All those years of electrical engineering before I changed over 
> to physics have gotta pay off.
>
> Rick
> Sent via BlackBerry by AT&T
>
> -----Original Message-----
> From: "Hans E. Hansen" <FList [at] hanshansen.org>
>
> Date: Tue, 2 Dec 2008 17:12:50
> To: rolindsay<rolindsay [at] yahoo.com>
> Cc: The FerrariList<ferrari [at] ferrarilist.com>
> Subject: Re: [Ferrari] Mondial owners - electro-technical question
>
>
> 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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