alternator plug on 315 yanmar

[saltshaker28]

The plug that plugs into the alternator on my 315 Yanmar has three wires a blue a red and an orange the orange wire has a butt connecter on it but I can not see where it goes or if there is another wire that it plugs into any help would be great

[sweetwater]

What year? I have an 05 and can take a look at mine.

[saltshaker28]

It is an 02 with the 315 Yanmar thanks

[sweetwater]

I was able to take a look today at the alternator, and there is an orange wire on my alternator also. I was unable to see exactly where it went because it was wrapped up in the wiring harness in the engine. I peeled it back as far as I could and did not find any connectors on that wire. I would look into that bundle(by the alt) and see if there is an open wire in there. Is everything working in the electrical system?

[saltshaker28]

Thanks for your time Sweetwater Iwill get it figured out sooner or later

[carolmarie]

I checked the wiring diagram in my service manual. Appears that the alternator has only a red and blue wire (plus a black ground). The only orange wire I could find was the one from the tach sensor to the tach instrument in the panel.
carolmarie, 2001TE, 6LP-STE.

[saltshaker28]

Where is the tach sensor located?

[sweetwater]

On the bellhousing

[saltshaker28]

I called Mack Boring and spoke with a tech who told me the orange wire on the plug that plugs into the alternator goes nowhere only the blue and red on the plug are used

[Halcyon]

The spare wire on the alternator can be used for a tachometer. There is also a flywheel sensor on the bellhousing. You have to be careful how many tachs are connected as the signal will deteriorate. I have three connected to each bellhousing sensor, upper and lower stations and Flowscan tach and the engine synchroniser is connected to the alternators.

[saltshaker28]

Now at least I know what the orange wire is for