Electrical Mystery #2

[John New]

First of all, I solved (with help from you all) the earlier problem with the boat electrics (a bad ground connection). Many thanks to you all, this is the very best of what the Web is all about.Here's the next mystery. While crawling around the wiring for the Yanmar 1GM10 engine on my 1981 Hunter 27, I came upon this female jack for a two or three blade-type plug (it's the white plastic one-a little out of focus,sorry-sticking up in the center of the photo next to the air filter intake)just aft of the starter. The three wires going into the jack join the bundle that goes to the two plugs that connect the wiring to the cockpit instrument panel (in background). The jack is on a short wire (3-4"), suggesting that it plugs in locally or that the mating plug is on a longer wore. But I cannot find ANYTHING that looks like it should plug into this jack and I spent almost an hour-with a flashlight-looking). I can't find anything that corresponds to it in my Yanmar manual (it's not a connection to the oil pressure or water temp sensors-I've located those). Everything seems to work just fine otherwise, but it's driving. me. mad. Or is it just decorative?Any ideas? What plugs into this? (and let's keep it clean )

 

[seadaddler]

Go To Sleep

I have seen extra connections on boats cars and trucks,could have been for what ever.If everything is working OK get a good night sleep,if it'snot broke than who cares go sailing and have fun.Nick

 

[Ed Schenck]

Test it with a voltmeter.

My guess is that it would plug into the back of a higher amp alternator. Your alternator is probably the 30-amp Hitachi. That alternator does not require an exciter voltage. The Hitachi 55-amp and higher do need an exciter voltage to "charge" the field windings. If you do not see two spades on the back of the alternator in a recess and looking kind of like an 'L' then you do not need that plug. If you did have that and it was unplugged from there your alternator would not be charging your batteries. Sometimes if you mostly daysail and then plug into shorepower you don't even know that your alternator is not working. If that plug is the exciter voltage then it will have 12 volts while you have the key or button on 'start'. The other wire is probably for an ammeter. Just a thought.

 

[GuyT]

Just a feature or option you dont have.

Many times the engine is wired for "soup to nuts" configurations. My dad used to use that saying alot - "everything from soup to nuts" and "the whole kit and kaboodle" - you know the older you get, the more you sound like your folks.Anyway, if you have the soup but not the nuts, then the connector is left hanging.I have a few connectors to nowhere on my 3gmf and wondered what it was for. Still havent figured it out yet - 3 years later. Not high on the priority list.

 

[Karl Wilmot]

Extra Wire

We recently, (two weeks ago) had the 1GM10 out of 27 Hunter. A friend removed and re-installed it, as he was hooking up the wiring, I noted that he hadn't plug the wire you described into any other connection. I asked about it and he told me it was for an option the boat didn't have. Some automatic something or other but I can't remember the option. The engine started and ran fine without it so I simply taped it off and left it alone. One more mystery on the road to getting under way.

 

[Skip]

could it be

There is a connection for an hour meter and also there is a connection for a tach that runs off the alternator output.