The oil pressure switch on 1992 Lexus es300 is located just besides the engine.
One possibility is that your sensor is bad...
There are quite a number of dashboard lights on Lexus ES300. The common ones include handbrake light, check engine, temperature, check oil, battery light and so many others.
Usually in the oil pan
Oil level is low. Serious engine damage will occur if this is not corrected. Check the oil level!
by oil pan
5 quart
5w30
It should be right under the exhaust manifold and in front of the radiator. From the front view its in the middle of the engine.
At the lowest point inside the oil pan.
Feel around the edges of the engine oil pan and you should find it. -However a few cars do not have them and the entire pan has to come off.
It is located under the exhaust headers, front and center.