Overheat Alarm 25HP Tohatsu

[emarshbuck]

My local boat mechanic rewired my boat using a new ignition switch, and installed a battery shut off switch. He did a nice job and cleaned up the wiring "mess".

Everything works except the overheat alarm. He knows about the yellow wire and all, but could not figure out why it doesn't work. The buzzer works when power is applied to it, but not when wired in properly.

Is it possible the overheat sensor needs to be replaced?

thanks

ed

 

[pvanv]

If you ground the sender wire, the overheat sensor should signal an overheat. What is your actual model?

 

[emarshbuck]

25 MFSA

Do you mean, ground the yellow wire feeding the overheat alarm?

 

[pvanv]

On the 3-carbed MFS25A, there is not any yellow wire feeding the overheat alarm. See p 60 of your owners manual, which you can DL from Tohatsu.com.



It's the wire going to item 41 in the above diagram.

 

[pvanv]

From the schematic on p60 of your owners manual, it seems that the sender wire is light green.
There are 3 yellow wires from the 3-phase alternator, as well as a yellow tach ground that runs with the white tach signal wire (and branches to the stop switch, and of course the yellow PTC heater wire.. So nothing in yellow has anything to do with the overheat sensor. What yellow wire are you talking about?