Fiesta 1.1 Oil Pressure Lamp

It should be on but that's because there's no oil pressure, not because of the presence of a self test.

No. Sounds like you need a new sender unit.

Or the connection could have fallen off the sensor or the contact is dirty.

But on other such lamps such as low water/washer/fuel lamps come on despite there being just as much or whatever substance after the engine is switched on.

As does a coolant temp warning Lamp.

Tom.

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Pull the wire off the sender unit on the engine and earth it. (with the ignition on) If the oil light comes on, you need a new sender.

Steve

Tom Burton wrote on Fri, 07 Oct 2005 17:40:49 GMT:

Yes, but why waste money designing a self-test system for a sensor that will (if working correctly) come on when the ignition is on, but turn off with the engine started? There won't be oil pressure and there won't be enough voltage from the alternator unless the engine is running, hence why they come on if you stall.

Of course more complicated systems where there's computers involved may do it anyway...

Indeed I do!

I unplugged the lead at the sender and grounded it. The lamp came on.

Damn. I only did an oil and filter change two weeks ago. I'm guessing I have to drain the oil to change the sender? Or is it ok 'cause all the oil is in the sump and the sender is above the surface of the oil?

No, you won't have to drain anything. Just remember to fit the new switch before starting the engine...

Chris

It doesn't need a self test circuit as it should be on when the engine is stationary, and go out when started.

Find the oil pressure light switch on the engine. Unplug the wire and ground it. The light should come on. If it does, replace the switch. They can and do fail. If the light doesn't come on with the cable grounded you have a wiring etc fault elsewhere.

Fitted new sender with what looks like a universal part from the local motor factor, £4.40.

Works a treat. I no longer have to worry about my engine exploding on me without warning. LOL! :)