Odd sender wire Yanmar 3JH4E

[MalcolmP]

Just recommissioning our 39i after being laid up for past 12 months. Just had one of those "wonder what this ?" moments, when I spotted an unattached sensor wire behind the alternator. The engine is a Yanmar 3JH4E.



In the photo hopefully you can see two thin white with black wires, one is attached to what I presume is a temperature sensor on the coolant circuit. But the other has ring connector, but no obvious place where it might have come from. Engine runs fine with no warning lights, can anyone enlighten me?

Thanks Malcolm

[moonshadow]

I can’t see the wire in question on your photo. But if you have a monitoring system they often have alternator temp sensor that looks as you describe.

[MalcolmP]

Sept 19, 2021 14:11:35 GMT moonshadow said:

I can’t see the wire in question on your photo. But if you have a monitoring system they often have alternator temp sensor that looks as you describe.

Thanks Moonshadow, the wire is the one with the small black rubber cowl guard in front of the alternator pulley. Think it may simply be a duplicate, but would love to be sure!

[MalcolmP]

Apparently the guys on the Yanmar Owners Facebook group are sure that it is an additional wire if you want to add a temperature gauge. Makes sense I hope...

[mesteve]

I have a wire like that that is on what I assume is a temp sensor in the thermostat housing

[sailingabe41ds]

hi..
im certaint that is for the optional temperature gauge if you had c type panel.  there is a similar additional wire for an oiil pressure gauge burried within a bundle of wires on the oiil alarm sensor side.  i can only get a glimpse of that wire and i did not want to take that bundle apart.  it is in the yanmar systems diagram.

abe