A couple months back I bought a 1974 FJ40. After playing around with all the electrical components I noticed that the previous owner disconnected the oil pressure gauge. When using the multimeter I was able to get a reading between the disconnected cable that goes to the dashboard and the battery. After reconnecting the cable and starting the engine, the dashboard seems to give a reading within a range. Not knowing much about these cars, is there a reason as to why the previous owner would have disconnect the oil pressure gauge?