oil pressure light

[lezmtaylor]

My Oil pressure light does not come on.
Is there a fuse?, can't see one in the fuse box.
Have fitted a new oil pressure switch to base of oil filter housing , light still not coming on when ignition is switched on.
Is there a bulb in the instrument pod ?


Lez

[X5Sport]

Sounds like an indicator fault.  Try putting 12V one side of the sensor and a lamp on the ground side and see if it goes off.  LED I think on the PCB.

[sleepyfolk]

Was it working before you fitted your instalube?

[lezmtaylor]

Was working AFTER I fitted Instalube.

Lez

[lezmtaylor]

Am I correct in the way I test to see if the oil pressure light is working ?
Disconnect the plug connector from the oil pressure switch, Then connect a piece of wire to the little connector inside the oil pressure connecting plug put the other end of wire to earth and switch ign on, I am thinking the OP light should come on.( It is not).
Any other suggestions welcomed.


Lez

[henrym3]

Can't remember if the plug is single wire or 2 wire, if single wire then what your doing should work. All you can do is trace the wire back as best you can and check for damage/break. Most probably instrument cluster fault. If you have wiring diagrams  you could check for continuity at IC multi plug. If your not one of these Black Magic electricians, NIGHTMARE. Good Luck
I'll see what progress you've made tomorrow when I get home from work and if needed I'll let you know what does work by disconnecting mine and putting a wire to it.

[lezmtaylor]

Mine is a single wire in the plug.
It is peeing down with rain here today, so have not been able to further investigate.
Going to whip the instrument pod out and have a look at the leds. and if it stops raining check wiring.
Will be interesting to see if yours works .

Lez

[lezmtaylor]

Stopped raining this afternoon SOOOOOOOOOOOo took the rev/speedo pod out and removed the 3 harness  plugs from the back of pod.
there are 2 plugs on the rh side at rear and one on the lh side at rear of pod, the lh side one is adjacent to the oil pressure light.The colour of the wire to oil pressure  switch is brown and green. In the lh side plug there is a number of wires, one of which is  brown and green, got meter out and put one probe on g/w at plug and other probe on g/w at he oil pressure sender plug , set meter to continuity and hey presto got a reading.
So the problem has to be with the diode.
Does anybody agree ??

Lez

[X5Sport]

Sounds reasonable.  Is there a connection all the way through to chassis as well down the same wire?

How many wires on the OPS itself?

It may not be the way BMW use it, but one way of bringing the indicator on is to power it from the binnacle and ground it via the OPS with the switch effectively breaking the circuit once the pressure is above minimum.

A quick way to check is to meter from the binnacle end of the wire to chassis via the switch and see what the resistance is.  If it is a simple switch then at zero pressure it should be a near dead short.  With the engine running it should be open circuit.

You can do the same test with the binnacle in and the wire lifted off the OPS and just meter between the OPS and the chassis.  If two wire then do the same across the pins.

The tricky bit will be if BMW are sending 12V down the wire but using logic in the binnacle to control the indicator in which case there could be other components in the indicator circuit.  Hoping they have gone 'simple' though.

The LED may just have a resistor in circuit as some don't like 12V direct through them.  Not always the case.

[lezmtaylor]

Thankyou x5sport,
There is a single wire in the OPS,
I'll investigate more in the morning, it's a weird one .
Will carry out the various tests you advise.
Regards,
Lez

[Horizon]

https://www.linkedin.com/pulse/engine-o ... l-mucevski

[X5Sport]

Perfect.  Great find    That's what I hoped it might be, a simple switch.  Also hoping that the supply comes from the binnacle and the switch makes or breaks the ground return so turning the light on or off.

[sleepyfolk]

Maybe your new OPS was just a duff one, on a side note - just got stung by customs for my instalube!

[lezmtaylor]

Thanks to Horizon,X5Sport and Sleepyfolk. gonna have fun tomorrow !!

Lez

[henrym3]

All that info seems clear enough and just to add, if I switch ign on, light comes on, unplug OPS it goes out. Plug in, start up and light goes out. Finally with ign on and light on, unplug and light goes out, put a wire in the plug and earth light comes on. Confirms diagram. If you have checked the earth path then it's either the power wire or light itself.