CAT 3116; Oil Pressure signalb switch

Hello everyone Breaking Out Another Thousand

I will introduce myself by posting another problem I have Princess 380 with twin CAT3116 engines

the low oil pressure alarm and the dash warning light doesn't go off when I start one of the engines (let's call it engine1). I know that oil pressure is ok because the oil pressure gauge is working and showing a good pressure. The warning light and the warning sounder is operated by oil pressure switch ( photo attached) and the oil pressure gauge is operated by oil sender.
I thought that the problem is in the oil pressure switch, but If I disconnect the oil pressure switch on the good engine ( let's call it engine2) - the alarm stops immediately without even starting the engine.. It doesn't happen the same on the engine1. I am not sure if there is another component like a relay involved in this...
Any help how to find a fault or diagram hugely appreciated