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2005 Mercury 90hp 2 stroke constant alarm

M

MIboat

New member
2005 but new to me boat, 90hp 2 stroke has a constant alarm that comes on when you turn the key and stays on. At 1st thought it was low oil alarm as oil was around half, but filled it up and alarm still comes on. Motor seems to be functioning normally otherwise. Any trouble shooting steps I could take??
 
Could still be a low oil alarm. Not sure how to 90 was setup, but the 225 had a oil level sensor that worked by a magnet. Only problem was that magnet often separated from the float and would just sit at the bottom of the tank making it read empty.
Either way, a constant alarm is not a good thing and you need to verify what is causing it before you destroy the engine from a wrong diagnosis
 
faztbullet said:
Either alarm module or float in tank.....common problems
Click to expand...
Both can be unplugged to isolate the problem, one at a time. As I recall, with the alarm module, only the low oil alarm is modulated...non constant blast, to distinguish it from the Over Temp alarm. Without the module, and some of these engines didn't have one, it's constant for either.

The OT alarm is a tan/light blue striped wire and the two wires coming from the oil tank are light blue with a white stripe. Since the oil sensor is a series circuit, you only have to disconnect one of the two wires to test.
 
Really appreciate the quick replys! Disconnected the oil sensor and alarm off. This group is awesome. Hope I can return the favor
 
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