Oil alarm

[steplift20]

Yes spare, 1988 150 Mercury blackmax.
I know how to check the oil cap using a multimeter ,I'm just a hour away now from my boat and I did replace it about 3 years ago
The oil pump motion sensor. I do have my old one cause I did replace that too a long time ago, can you bench test the motion sensor? From what I see. The oil cap tells you if you have low oil
The motion sensor. Monitors the internal gear. So there are only too things left in case they check out good
The warning module. And the internal gear. But I'm not jumping to conclusions yet. If it's anyone of the last two I mentioned. Than I'm screwed. Just have to convert it to me mixing oil and gas but I don't know how to do that.