Mk1 Oil Pressure Warning Circuit

[V Mad]

My engine oil pressure warning light was not working, so I spent a while investigating why. I discovered that the lamp receives its supply via the brake line failurewarning light (the big red one in the middle. This is weird because the it means thatif either bulb blows, the other goes out; also if the brake line pressure switch has set (closed) the engine oil pressure light goes out. The other effect is that, because of the other light,the all important engine oil light does not glow very brightly as it does not get the full battery voltage.

In my case, the brake line lamp had been removedpresumably because theline switch has closed causing lamp go go very bright(switch needs resetting I think as brakes work OK).

Weird and confusing circuit. I thinkthe Mk2 versiondid away with this sytem.

[martin]

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Hiya, the Mk2 is the same, no one can tell me why, it's daft. Martin.

[DJT]

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The system is set up so that the brake warning light comes on dim with the ignition as a lamp check and goes out as soon as oil pressure is sensed.

With my Stag I discovered the brake warning lamp was missing. Put one in and it glowed all the time due to the brake PDWA being off-centre. Reset that and it went out. I now find that the brake lamp does not glow on turning on the ignition. The oil light behaves correctly, and the oil pressure is good. I know the brake warning lamp is good, but I cannot see why it doesn't glow when it should. :?:?

Any ideas?

Dave

[V Mad]

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martin wrote:

Hiya, the Mk2 is the same, no one can tell me why, it's daft. Martin.

From the schematic diagram in the Technical Reprints articles, which represents the Mk2 carthe engine oil pressurewarning lamp works independantly.But the brake line warning circuit is now paralleled up with the handbrake circuit; I suppose that makes sure the lamps always get tested when you apply the handbrake.

[martin]

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In mine, a Dec.'74 Mk2, the oil light is in series with the PDWR light and the handbrake lightis independant. Don't know when it changed. Martin.