oil light prob 2.4 ln130

[dieselboy]

wonder if someone can help?
after i did my oil and filter today i noticed i dont have an oil light. when ignition is on there is no oil display light that i would expect to come on when engine is off. and when it starts there is no light that comes on then goes out or anything.
my oil pressure is always on the 1st mark at tickover give or take a little, then when the engine picks up it goes right to half way. ive always kept an eye on the oil level. especially if i have been driving for long periods.
any ideas anyone?

[plumb bob]

Bulb blown/missing?

Loose/broken wire?

Faulty/missing sensor?

[dieselboy]

where would the sensor be? on the block or the head and where abouts?

im guessing the sensor would have only 1 wire on it. when this wire earths would it make the light come on or go out? ill do some tracing when it stops $$$$$$ raining.