Toyota Repair: oil light switch, mileage engine, main bearings

Question
1989 Toyota corolla automatic.The dash oil light comes on while driving but the oil level is perfect.If I am to change this switch ,where would I find it?and is there other things I should check for?thx mark

Answer
Mark,

The oil switch is located on the driver side threading into the back of the cylinder head.

Just because the oil level is good does not mean it can't loose oil pressure.  If it is a high mileage engine your main bearings could be worn out or the engine could be sludged. I would suggest hooking a mechanical gage in place of the sending unit temporarily to verify you have good oil pressure on the engine. I don't like to see the pressure drop below 5-10psi at hot idle in gear.