My Mazda eunos has an oil pressure gauge but not a light, i would like a light as well.
i plugged an LED into the pressure sensor terminal,turn ignition on.light comes on,gauge stays at zero, start engine,needle goes to it,s normal place the LED nearly goes out,just a feint glimmer.
so,any way round this,would a resistor put the light out when the engine has pressure or do i have to go about installing a pressure switch.
on the other side of the engine is a plug in a gallery that the turbo boys use to feed their turbo,s, anyone know if this gallery has enough pressure to operate the switch ?.
TIA peeps

You will need an oil pressure switch

This is not that complicated. But firstly how did you wire the led?

If it is an analogue gauge, dial with needle, then sender is not an open/closed switch. The sender will likely have one end connect to 12 v and other to gauge input. Connecting any component is likely to affect tbe current/voltage seen by the gauge so will show a different reading compared to original wiring.

One solution is a comparator circuit that will turn led on or off at a set pressure.

Can you measure voltage at the guage when no pressure and engine running?

quote:

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Originally posted by 02GF74
One solution is a comparator circuit that will turn led on or off at a set pressure.

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cheers guys

I'm sure I fitted a different sender that does both. Direct replacement, cost about £10.00. Will check tomorrow if interested.

yes please smokin frog

quote:

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Originally posted by Smoking Frog
I'm sure I fitted a different sender that does both. Direct replacement, cost about £10.00. Will check tomorrow if interested.

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Or t-piece like this:



See http://www.vehicle-wiring-products.eu/product.php/218/t-piece-adaptor-1-8-nptf

obviouls depends on thread of the block/senders but there probably be one that suits.

had a look at T pieces,there isnt a lot of room for one,i lost a pint of blood fiddling down there yesterday

The one fitted to mine is a twin post vdo sender with a thread adaptor. So it's not a direct replacement. Not that cheap now. Quick look on ebay more like £25.00 + adaptor.

Ok thanks,i like the dual function idea,ill have a look see if i can get one.

25 will buy all the electronic components and lea e change for several pints.

Can you measure resistance across sender when disconnected and voltage at gauge with ign on and engine not running amd running.

A single transistor/resistor/diode circuit coukd work to turn on the led.

Alternately capillary tube to a t piece that is away from the block.

sorry 02gf75,my limit in electronics is soldering a couple of wires together,ill go for the T piece idea as it is more in line with my abilities

found a sender that should fit the bill,the ohms readings go from 10 to 180 according to the seller but my book of words says the sensor on my car goes from 52 to 160 so......will it work ?

This link does suggest "Sender with 0-80 PSI measurement, 5 bar, 10-180 ohms (larger PSI ranges will provide less accurate readings on the Miata cluster)"
https://sites.google.com/site/redcapsmiata/tutorials/mazda-miata-oil-pressure-sender-upgrade

Here's cheap one that seems to fit the bill (that is IF the description is accurate). But it will be on a slow boat from China.
Genuine Oil Press Pressure Gauge Sensor / Type 80psi 10-180 ohm two terminals
Obviously would still need an adaptor.

^^^ same as i was looking at.
googling seems to say the thread on the original is 1/8 npt,others say bsp....oh well it,s only £8

As far as I'm aware 1/8 BSPT. Here's a cheap adaptor, but check if it's the right one as I'm going from memory!
BSP-NPT Adapters , Male BSPT to Female NPT Exten in Brass, European to American

cheers all,ill get the bits and nail him together now :-)