Yamaha V4 115 BETO overheat alarm query

[stop8stop8]

Hi Folks,

I have just changed the impeller and both thermostats on this engine.

The over heat alarm sounds constantly even before I put the boat in the water.

I disconnected the thermo switch port side and the alarm stays on, disconnected the thermo switch starboard side and the alarm remains on.

I traced the cables back from the thermo switches and there are no breaks or burns and look ok however both wires for both thermo switch wires join together and then go into one connector. This connector has some sort of diode or resistor that was broken. (see pics)

Just got back from the Yamaha dealer and they had no idea what it is and it does not appear on their workshop spare part diagram so could give me any info or order replacements

I have attached two pics.

Any ideas what this is part is and if it can be removed and the wires connected directly?
Is this an after market modification and why?
Would this broken piece cause the overheat alarm to stay on constantly.

Any help much appreciated.

Thanks
Andy

[99yam40]

what makes you think this alarm you hear is the overheat?

what do you mean by "The over heat alarm sounds constantly even before I put the boat in the water"?
are you running the motor before you put it in water to cool it?

I have no ideea what that is that broke

[boscoe99]

Please provide the engine ID.

How do you know that it is the over temperature alarm that is sounding? Do you have the Yamaha tachometer that tells you so?

[stop8stop8]

There are only two alarms that sound, the constant alarm is the overheat and the intermittent alarm is the low oil level.

This alarm is a constant beep.

As soon as I turn the boat key one click to the right the alarm is on even before I leave my drive way. I am not running nor have I ran the boat out of the water.

The alarm goes off when I disconnect the connection joining the pink wires as per the photo so it is associated to the thermo sensors.

Engine ID is 115BETO, 6E5 L 365624 and a Capital C in the right hand bottom corner of the plate.

[99yam40]

I never heard of Yamaha having different alarms for over heat and low oil.
ground the pink wire usually set the alarm to a steady buzz.

how do they make the alarm intermittent for low oil?

[stop8stop8]

The Yamaha dealer said a constant steady buzz from the throttle controls is overheat and a buzz that pulses 3 times every few seconds is low oil warning for the premix.

Today with both thermo sensors completely disconnected the constant buzz alarm was on. The only way to shut it off was to disconnect the wire coming over the top of the port thermostat housing in the photo.

How can an over heat alarm be going of with both thermo sensors completely disconnected, very weird?

That why I though maybe that resistor or whatever it is in the other photo had something to do with this..?

[stop8stop8]

Ok so I have just been back down to the boat, turned the key and no alarm sounded. I removed the filler cap from the oil deposit and the alarm sounds so I topped it up and now have no alarms.
Don't know why the local dealer gave me random advice about the alarms, but then this is Spain!

I would still like some guidance on what that broken resistor or whatever it is may be and if I can simply remove it from the thermo sensor connections.?
Cant find it on any of the workshop manuals I have what the dealer gave me today

Thanks again

[boscoe99]

Ok so I have just been back down to the boat, turned the key and no alarm sounded. I removed the filler cap from the oil deposit and the alarm sounds so I topped it up and now have no alarms.
Don't know why the local dealer gave me random advice about the alarms, but then this is Spain!

I would still like some guidance on what that broken resistor or whatever it is may be and if I can simply remove it from the thermo sensor connections.?
Cant find it on any of the workshop manuals I have what the dealer gave me today

Thanks again

It is not uncommon for Yamaha to embed components within the wire harness that are not depicted on any Yamaha documentation.

[stop8stop8]

I have been speaking with a good friend that is a marine electrical engineer and we have reached the conclusion after studying the wiring diagram and the possible purpose of this piece, that it is a diode.
I will test with a multimeter on Monday and replace with something like for like I can get locally.

Thanks again for the guidance

[pstephens46]

Why not eliminate the piece and wire it back together? What’s the worst thing that could happen? You could could still test to make sure thermoswitches will work properly.

[boscoe99]

[99yam40]

I am guessing that the diode is there to keep the oil and overheat lights from both lighting up when one or the other comes in but still each will sound the buzzer

[stop8stop8]

Thats great work on finding the diode info, much appreciated. Ill certainly look more into it.
Thanks again for some great support