Yanmar 3GM (Hitachi) Alternator Wiring Diagram - SailNet Community
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post #1 of 9 Old 01-25-2011 Thread Starter
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Yanmar 3GM (Hitachi) Alternator Wiring Diagram

My original Yanmar 3GM engine had a 35 amp Hitachi alternator with a E (ground), B (Batter +) and a L (Lamp) connection. The replacement alternaotor (used on later model engines) in addition to the previous connections has a R connection (could mean regulator). The Yanmar wiring diagram for this R connection is conflicting.

I think the R should be hooked to a 12 volt + when ignition is on, but the wiring diagram shows wires crossing at this connection. To make a connection the diagram should show a dot and to not make a connection the wire should show a half circle at the intersection. Neither is shown so not sure if it is really a connection to the 12 volt +.

Does anyone know if the R should have 12 volt +?
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post #2 of 9 Old 01-28-2011
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I believe the Yanmar Shop manual will have a electrical schematic of the oem altenator that was provided with the 3GM30F.
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post #3 of 9 Old 01-28-2011 Thread Starter
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FYI,
Found some other wiring diagrams and the connection for the "R" connection goes to the 12 + that is powered when ignition key is "on". Some repair manuals show this connection as crossed wires when to make it clear there is a connection there should be a dot where the wires cross on the diagram.
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post #4 of 9 Old 02-03-2011
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I have a 4jh2e and the replacement altrrnator I put on has the R post labeled a/c tap - tachometer. I have no wire on it though, so I guess my tach gets it info elsewhere.
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post #5 of 9 Old 02-09-2011
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i just installed a mitsu alternator on my westerbeke. I took it to a local shop and he was able to test the unit, he told me that "R" was either tach or hour metter.
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post #6 of 9 Old 02-09-2011 Thread Starter
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My engine gets the tach in put from a senor near the fly wheel. I think what I will do is not connect the "R" terminal and see if the alternator will charge. If it does I will not connect it. If it does not I will connect it to the 12+ (on when ingnition key is on).

I fixed the existing alternator so I will not need to change until it goes out. My alternotor lamp on yanmar panel never came on- turned out to me a bad connection at the connector plug on the wire harness. Open the connectors up an spray some anti corrosion spray on them to maintain good connection.
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post #7 of 9 Old 02-10-2011 Thread Starter
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Quote:
Originally Posted by nolasailor View Post
i just installed a mitsu alternator on my westerbeke. I took it to a local shop and he was able to test the unit, he told me that "R" was either tach or hour metter.
If you look at the yanmar wiring diagram for a 1gm, 2gm or 3 gm the tach input is from a sensor near the flywheel. The signal is not coming from the alternator. I am not sure how the newer yanmar get there tach signal. It is true some engines get the signal from the alternator.

On the Hitachi alternator the connection is not lableled "R", the connection is actualy where the two conductor conector would connect to the alternator. Some diagrams I see refer to this as the "R" conection.
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post #8 of 9 Old 08-27-2012
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Re: Yanmar 3GM (Hitachi) Alternator Wiring Diagram

I'm fully restoring a 1978 Nicholson 30 1/2 ton designed by Ron Holland. I completely rebuilt the Yanmar YSE 12 on the boat. The boat came with a VDO insturment panel but the tach does not function. I'm interested to know if there is a sender available to retro fit the engine? I really don't need a tach as all other gauges are functional, guess I'm just too ticky. If anyone has a handle on this I would like some workable feedback. I located the VDO panel with diagram that has a sender unit from the generator to the tack with dip switch settings for various RPM's but the sender looks to be missing or was never an option.
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post #9 of 9 Old 08-29-2012
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Re: Yanmar 3GM (Hitachi) Alternator Wiring Diagram

Unless I'm reading it incorrectly, Far Side, your question is worthy of its own, new thread where it can have a subject line of its own. You might get more relevant answers that way than by having it attached to an older thread of only peripheral relevance.

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