Sudden low oil pressure ...... sensor fault?

[mittens]

Electrokid ..... I'm in Swanley, Kent.

[Vanny]

http://205d.free.fr/compteur.htm

An interesting thread (in French) which details the steps taken to fit diesel cars with the oil sensors (level and pressure) which I think might be relevant to this thread for others

Edit
I've seen a few times (on Renault forums) that the Elex 14307D is sometimes used instead of the Ti chip, though I can't find a data sheet for that either

[electrokid]

Electrokid ..... I'm in Swanley, Kent

I think Remy is still on here as medwaycitroen though I haven't seen him post for a while...

http://www.medwaycitroen.com/

Further afield - Rob Moss of Chevronics is on here - sorry Rob - can't remember your username

http://www.chevronics.co.uk/

And Malcolm at St Leonards-on-Sea is on here as Citronut - very helpful.

An interesting thread (in French) which details the steps taken to fit diesel cars with the oil sensors (level and pressure) which I think might be relevant to this thread for others

That's a useful link Vanny - thanks. I have all the bits to do this but it's still on the never-ending to-do list.

Does anyone know or can guess the earliest date that the TL527N was fitted ? That may help me locate an appropriate databook. I do have a box of old databooks in the garage but TBH the North Face of the Eiger would be easier at the mo

[Vanny]

You'll have to excuse my ignorance as i havent really studied the circuit, but is the chip simply selecting an input based on a voltage? In which case could it be something as simple as a voltage comparator like this;

http://pdf1.alldatasheet.com/datasheet- ... E527N.html

I think i'll have to dig the switching module out and work out its wiring schematic . . .

[Way2go]

The chip functions as a timer to switch between the default mode (oil level) and oil pressure but maybe does contain addition functions to interpret the level sensor?
Perhaps a 555 timer chip or similar can be piggybacked in to correct the operation?

[electrokid]

That NE527N is quite possibly an equivalent. Any comparator or threshold device could do the job - stick a CR time constant on the input and you've got a timer.

[Way2go]

The 555 is a ubiquitous and cheap device so strage that it wasn't adopted if ok but this is Citroen and Veglia I guess?: :lol

[Vanny]

A 555, although great for simple and hobby work, does has some fundamental limits for automotive work, such as a limited operating range. Generally i try to avoid them as timers as there are better solutions.

[electrokid]

The 555 is an excellent IC which is let down by the application notes. The suggested circuits and the cumbersome maths that go with them are a pale reflection of what is possible with this IC - in one instance a suggested circuit and its associated math only work if you are very very lucky and if it's a full moon. There are many novel configurations which work well including one which I've developed and not seen on the interweb - writing a web page on 555 configs is on my to-do list. I'll attempt to describe my design of 555 astable here...

Hook up all the 'normal' connections...

Pin 1 - ground
Pin 8, (VCC) and pin 4, (reset) to plus volts
Pin 5, (control voltage) decoupled via a 10nF to ground
Pin 3 is your output as normal.

You need a timing cap, a 'charge path' and a 'discharge path' to make it oscillate.

Connect the timing cap between ground and pin 6 (threshold) and connect pin 6 to pin 2 (trigger)
Connect a resistor (R1) between pin 6 and pin 7 (discharge path)
The charge path is...
Connect the anode of a diode (1N4147 is fine) to pin 3,
the cathode of the diode to a resistor (R2)
the other end of the resistor to pin 6 and therefore to the timimg cap

In this circuit, the cap only charges when the output is high and only discharges when the output is low. The charge and discharge paths are completely separate (as opposed to the nonsense in the application notes) and therefore defineable independently and also independently adjustable without compromising the operation of the IC.