Yamaha OX66 low oil alarm.

I have a 2000 Yamaha 200hp OX66.
The low oil alarm light stays on all the time.
Both oil tanks are full and I don't get any audible
alarm or have the motor slow to low rpm's.

Probably the sensor in the spare oil reservoir-thats what happened on my black motor at least

Sounds like you have an alarm module problem. I am not aware of a way to activate that light without activating the alarm. Alarm horn bad is all I can think of but even that should put the motor into protection mode.

The alarm horn works fine. I had a bad water pump and the motor would overheat while idling. The alarm would go off very loud. I don't have a wiring schematic. The light hsve to have a positive and negative going to it. Where do they come from? Which one is switched to activate the lamp?

The heat alarm doesn`t go through the alarm module. The heat warning sensor works as a ground to the warning horn when an over heat condition happens. The oil warning gets its warning signal from the main oil tank if it gets low and the motor mounted reservoir if it gets low on oil.

Gary
I replaced the main oil tank sensor and the motor tank checked out as good.
Checked the resistance per maintenance manual. The light still stays on.
I had a wiring problem with the motor tank a few years ago and the light worked
the alarm worked and the protection worked when the tank would get low.
Wish I had a good wiring schematic.

I just had an issue on my Yamaha where the oil alarm went off and the motor would not go over 1000 rpms. When they hooked it up to the computer they had 42 overheat alerts for the day. So you could have a similar issue.