Oil warning light switch diagnosis 3.2

[sus911]

Just recently and at about the same time, I noticed that both my alternator AND oil pressure warning lights failed to come on when I turn on the ignition.

The alternator light was an easy fix by cleaning the terminals and re-inserting the bulb into the holder.

The oil warning switch hasn't been that easy. I tested the wires at the light plug and there is constant voltage on the red wires with ignition on. Now I understand that the switch is connected to the light pretty much directly via a green/white wire which supplies a switched ground to the light. With engine off and ignition on, ground is supplied by the switch and then goes open at startup when oil pressure is achieved.

The bulb is good. I tested the green/white ground wire by disconnecting it at the switch and connecting it to a good earth on the engine then turned on the ignition. The light worked.
Can I conclude from this that there is continuity in the green/white wire and the problem is the switch?

[wazzz]

Yes, you checked everything correctly. The switch is obviously the culprit.

You should also notice that the brake pad wear light no longer goes on when you switch the ignition on. It should go on again for test once the oil pressure switch is replaced.

[sus911]

I couldn't find an answer to the question of needing to drain oil to remove it with engine still in the car?

[Flat6pac]

Take filter box off and you ll be able to see the oil light switch.
Bruce

[sus911]

Thanks Bruce I'm there now. Just not sure if oil will come out if I take the switch off. I doubt it...

[PeteKz]

Not unless it's running while you do it.