Yanmar 2GM Temperature sender.........

[petermills]

I'm pulling my hair out over this.......
There is no guage - just a warning light and buzzer which operate when overheating occurrs.
With the disconnected sender in a pan of overheated water, there is continuity between the body of the sender and the single terminal. When the water cools down, the continuity is broken.
Temperature sender has just one wire connection. With the Starter switch in first position, the oil pressure and charging lamps light up and the buzzer sounds. The coolant warning lamp does not go 'on'.The temperature sender wire has 12 volts on it. Can someone explain what happens to this 12 volt supply when the engine overheats??? To me, it seems that the 12 volts would go direct to earth when the switch senses overheating.
Any ideas ?????

 

[VicS]

There is 12 volts fed to one side of the warning light bulb.
The sensor connects the other side to earth/ negative when it senses overheating.

While the temperature is normal the sensor is open so you will be able to measure 12 volts on the interconnecting wire.

There appears to be some variation in the exact way in which things work depending upon which panel is fitted.

You have tested the sensor and that appears to be ok.
When running normally if you short the connection on it to earth the warning light should come on and the buzzer should sound.

There are wiring diagrams in the workshop manual at http://www.motoren.ath.cx/

 

[petermills]

Temperature sensor...

Thanks for the above reply. Everything works as you suggested - buzzer and warning lamp come on when the sensor wire is grounded.
I checked the website that you recommended but there was'nt a wiring diagram there......??

 

[VicS]

Thanks for the above reply. Everything works as you suggested - buzzer and warning lamp come on when the sensor wire is grounded.
I checked the website that you recommended but there was'nt a wiring diagram there......??

In the GM_HM workshop manual. First one in the list of Yanmar manuals
Several wiring diagrams right at the end. Page 231 et seq.