Alarm sounding intermittently 1989 90 HP

[PickyBiker]

I found a schematic online for a 1986 90 HP, but that should be about the same as my 1988 90 HP. It appears there are 4 things that can sound the alarm; 2 temp sensors, an oil level sensor, and the VRO pump.

It looks to me like any one of the 4 can provide a ground path to cause the alarm. I should therefore be able to disconnect each item and test for ground to see which one is causing the alarm to sound. Please advise if I do or don't understand this correctly.

[boats.net]

Intermitten is oil alarm, pump oil primer bulb hard to reprime and that don't work may need new VRO.