alternator problems on h37

[Jack Betts]

I have a 55amp Hitachi alternator that replaced a 35 amp alternator on my Yanmar 3QM30 some time ago. Currently there are two wires connected -- one from the lower part of the back of the alternator, and the other to the lower (and vertical) of two spade-type connectors within a plastic housing. The upper spade connector, which is horizontal, is not connected to anything. Nearby, taped off on a piece of rigid tubing is a brown coiled wire with a spade connector on its end -- but unconnected to anything. I suspect this might have once been connected to the 35 amp alternator, but evidently it was never connected to the 55 amp alternator. 1. Can anyone tell me what this wire might have done on the original h37 with the 35 amp alternator? 2. Can anyone tell me what is the purpose of the horizontal spade connector on the 55amp alternator? 3. Might this wire have been connected to the horizontal spade connector on the alternator?4. And finally, occasionally (perhaps 5% to 10% of the time) my cockpit charge light flickers or glows red briefly. The alternator belt tension seems to be okay. Does anyone have a suggestion what might cause the occasional flickering (and momentary drop in the tachometer reading)? Could that be related somehow to the unconnected spade connectors? Thanks!

 

[Ed Schenck]

Check photo forum Jack, . . .

for a little help. I posted a wiring diagram there a few months back. But you have to use "Search", try "early wiring" as the argument.It shows three wires from the old 35amp Hitachi alternator. But it doesn't show a color for the ground wire. That could be your taped wire since the alternator is already grounded if the engine is. Then you have red to the battery and red-white to the amp light/meter.I still have the original setup on my H37C and will try to remember to check this weekend. Ed(schencked@bfusa.com)