Mercury alarm buzzer help needed.

[FlyingV]

I have a 1994 Mercury 115HP 2 stroke and the alarm buzzer is going off. Its a constant alarm which my owners manual says is an Overtemp alarm. The problem is, is that it does it when its first started and still cold. It does not do it all the time either. I put a pump impeller in it thinking it was maybe worn enough to cause the temp to up but it appears that that was not the problem. If I turn it off and start it up a few times, it will not buzz anymore but I can't find a pattern to it. There is a good stream of water coming out the water outlet jet and it is only warm to the touch so the motor appears to not be getting hot at all.

Anybody here have any ideas? I'm thinking it could be the temperature switch. Does anybody know where it is located on the motor?

Thanks for your help.

[hondavxr]

Is it an oil injected motor? If it is, the alarm could also be the low oil alarm. They both are the same sound. If your motor is not oil injected, it might just be your temp sensor going wacko, just replace it and you should be good.

[FlyingV]

Thanks for the quick reply. Yes, it is oil injected. My manual says the oil alarm is an intermittant (or pulsing) alarm? That's why I have been looking at the cooling system.

[LMITOUT]

Correct. The overtemp alarm is a constant tone while the low oil alarm is on/off tone.

I would start with the temperature sending unit also, especially if it's going off right when it is started cold. You may have to check the local library for a service guide or if you have a willing dealer they might help you out where to start.

[hondavxr]

D@mn, you guys are right. I just checked my manual. All I know is both those alarms are annoying as hell, and scary when you are in the middle of no where.

[marine_man]

I'd check the head on the motor or in the block.. perhaps on the top.

I believe the logic the sensor works on is when the motor is too hot it grounds the sensor, providing the ground to the horn... so if you find it, disconnect the wire and see if that solves the problem.. if so, replace the sensor and you should be in good shape...

marine_man

[FlyingV]

I finally figured it out. It was the Alarm controller module. Just under $100 to replace it.

Thanks for your help guys.

[LMITOUT]

Glad you figured it out and thanks for checking back to let everyone know what the solution was.