Oil Pressure warning light

[rbgosling]

I'm confused about the wiring of the oil pressure warning light...

First off, I can't find it in the wiring diagrams. Ignition light is on Sheet 3, choke/low fuel on Sheet 5, headlamp main beam on Sheet 6. The oil pressure gauge is on Sheet 20, but it doesn't show the warning light.

This symbol:



is on the gauges, I would interpret this as low oil warning, but it's not the conventional oil can symbol for this (Google AI thinks it's a laundry instruction, "do not wring dry"!). The owners handbook is of the impression that this light simply doesn't exist.

I replaced the oil pressure transducer on the engine at the resto show in March. I'm pretty certain I wired the new one in the same way the old one was; conveniently the new one has the two tabs labelled "G" and "WK", I assume "G" is for gauge, and somehow "WK" is for warning light. The "G" is connected to a White+Brown wire, which is consistent with the wiring diagram. Inspecting the wire connected to "WK", it turns out this is a black wire (slightly home-made looking) that leads back to the earth point on the AB14. Which certainly doesn't seem useful in any way. I didn't put it there, maybe a PO did, but why?

For context, my gauge hasn't worked for quite a long time. I'd hoped that replacing the transducer (which wasn't cheap) would fix it, but no luck. I'm confident the engine does have oil pressure - it would have died a long time ago if it didn't! - but it'd be nice to know how much! I may need to revisit the gauge...

[Hawaiis0]

I'd say G is Green; WK is White/Pink

and i cant find it either!

But sender should be WN white/brown

[Zag]

Gauge should peg right with transducer disconnected if all wiring correct. Looked through all electrical system sections and it looks like the warning light was missed.

[ebikediver]

In my previous career as a film lighting fleet engineer our silent running film generators all relied heavily on oil and temperature transducers and we had a very large stock of each mainly because of how notoriously unreliable new transducers proved to be. We would often have to fit 2 or 3 oil pressure transducers before finding an accurate one that we could rely on only after comparing with a known reliable oil fed gauge. Despite it's cost I wouldn't trust your new one without checking it against a reliable oil piped gauge.

[Marten]

I'm confused about the wiring of the oil pressure warning light...e...

Should it have a warning light? Nothing about it in the owners manual and the pressure transducer has a single connection on mine ('85)

If you have a switch for oil pressure they usually are closed with the engine off, open with pressure present. It is typical for the pressure to be stamped somewhere on the sensor. With a multimeter you should able to find out what's what, if the wires are connected to ground or carry voltage etc. G could also be used to indicate Ground

[rbgosling]

Curiouser and curiouser...

So, I pulled the gauge panel out. The good news was that the earth connection to the oil pressure gauge had fallen out - easy fix, and now the gauge works. (Shame I ended up buying a new transducer unnecessarily).

As for the mystery light - there's definitely a bulb in there with some wiring:
- Green, which is the general colour for power supply for all the dash gauges
- White + Orange.



A thorough search of the wiring diagrams shows White+Orange cropping up twice - between the Low Fuel Warning Lamp Delay Unit and the Fuel Tank Sender on Sheet 5 (but nowhere near the dash, and as we know the low fuel light is a different one, combined with Choke); and in the wires between the two door locks in the central locking wiring, Sheet 31. Neither comes close to the dash warning lights.

A cursory search of the engine bay uncovered no wayward White+Orange wires (although there was a Pink+Blue one, with a bullet connector on the end???). So, who knows where the other end of this White+Orange wire goes?

Anyway, I now have a working oil pressure gauge, which does make me a lot happier.

[Pete Boole]

Where does the low oil pressure warning light receive it's 12v supply from? In the normal scheme of things the bulb would get 12v and be earthed via the WK terminal of the sender when the oil pressure is low.

Pete

[rbgosling]

Where does the low oil pressure warning light receive it's 12v supply from? In the normal scheme of things the bulb would get 12v and be earthed via the WK terminal of the sender when the oil pressure is low.

Pete

Well, assuming that's what this lamp means, the power supply is the Green wire to the bulb, then the White+Orange wire leads from the bulb and, I would expect, should go to the WK terminal on the sender. But there's no sign of a White+Orange wire that end of the wiring loom. Oddly, there is a rather home-made looking wire that had been connected to the second terminal on the sender and went straight to earth - maybe a PO thought the sender needed earthing via this terminal and so installed one?

[Pete Boole]

So is the white and orange wire present at the dashboard end?

Pete

[rbgosling]

So is the white and orange wire present at the dashboard end?

Pete

Yeah, the White+Orange wire is coming out from the bulb, where it goes after that....?

I had a bit more of a look under the bonnet, tracing the sender-gauge wire back a bit to see if there was a cut end where some dafty had cut off the white+orange wire for some reason, but no sign of anything there.

[Pete Boole]

The engine bay wiring loom has a plug in the driver's side footwell - have a look to see if the white and orange wire goes as far as the connector.

Pete

[AndrewWebber]

Richard. The symbol on the light in your photo looks more like 'Low oil LEVEL' not pressure? I wonder if it illuminates if you switch in the ignition on having drained some of the oil?

Andy

[rbgosling]

Richard. The symbol on the light in your photo looks more like 'Low oil LEVEL' not pressure? I wonder if it illuminates if you switch in the ignition on having drained some of the oil?

Andy

Yeah, I see what you mean - but there's no sensor in the sump that would detect a low oil level. The only sensor that can detect a lack of oil is the pressure sensor that will tell you there's no oil 'cos there's no pressure.

[AndrewWebber]

Indeed, that's what my kids tend to do......

[MetBlue]

The lens is amber, which in my book means "carry on regardless".
If it was anything to do with oil or coolant levels,I would expect it to be red.
I'd guess it was planned to be used as a screen wash level in some markets. Might be worth looking in the non UK wiring diagrams.