Alternator replace on yanmar 1gm

[Starrfish]

My alternator needs replacing on my yanmar 1gm and there is not a part number. When I took it off there was only a red wire to battery connection. Two other wires dangled but were not connected. I have it at a shop to rebuild but it is too old and corroded. On a 1gm is there such a thing as a 1 wire connection or are there supposed two be at least two. Where does the second connect? At the "L" marking?
Capt Phil

 

[Steve Dion]

Contact your local Yanmar distributor. They sometimes have rebuilt units.

I am guessing that yours is a 35amp unit that was used on the GM engines, but they can verify that for you.

 

[waterbound]

alt. wiring

My alternator needs replacing -

I'm looking at my Yanmar service manual, alternator wiring diagram. I see that the "B" terminal should go to the battery (+), the "E" terminal to battery (-) and the "L" goes to the charge lamp. Ref: Chapter 10, page 22. Hope this helps.

 

[Scott T-Bird]

I'll look at my 1GM at home to follow-up, but I think you can select any 35 A alternator with the same footprint (it seems to be standard). You shouldn't have any problem finding a replacement. It may be that it has a 3-wire hook-up, but only the charging wire is connected, possibly meaning that the sensor wires are not functioning. I wonder if a 3-wire hook-up can function as a one-wire hook-up with the sensors simply disconnected.

Here is some reading on the difference between 1-wire and 3-wire hook-up. There is a nice summary at the end.

http://bob_skelly.home.comcast.net/~bob_skelly/alternator_conversion/wiring_alternator1.html

 

[woodster]

look for a Hatchie alt of the same size...that is the brand that Yanmar used on all i have ever seen ........

 

[Ken13559]

Yours could be Hitachi LR135. In my neck of woods, we don't bother repairing. Even with shipping cost, its cheaper to buy new from US ...that is right across the globe from where I'm at. Check out Gladiator Alternator from eBay site. Its very reasonable price and fit Yanmar.

 

[Bill Roosa]

With an internal regulator you only "need" one wire, the positive to the batteries. The ground is through the alternator body to engine to ground. and the charge lamp wire is not required but handy to indicate the alternator is in fact working. A volt meter can double as an indicator lamp so if you have a voltage meter on the panel you can just look at that to see if the volts come up when the engine is started. Would require consistent monitoring where the idiot lamp does not as the buzzer should also sound off if the alternator stops charging

 

[Stu Jackson]

Scott's link is very good, thanks, Scott.

Maine Sail wrote this some time ago, but it includes a discussion of Hitachi alternators that is very important to know.

http://forums.sbo.sailboatowners.com/showthread.php?t=125392

 

[Stu Jackson]

removed duplicate posthttp://forums.sbo.sailboatowners.com/showthread.php?t=125392

 

[Benny17441]

My alternator needs replacing -

I'm looking at my Yanmar service manual, alternator wiring diagram. I see that the "B" terminal should go to the battery (+), the "E" terminal to battery (-) and the "L" goes to the charge lamp. Ref: Chapter 10, page 22. Hope this helps.

To add to this the wire colors in the harness are Bat (+) Red, E (-) Black and L Blue/black. The OEM alternator is a 35A Hitachi but there are plenty of aftermarket replacement units. Amazon has a DB unit for $129. Do resist any temptation to go to a higher amperage unit. The 1GM does not have any spare Horsepower to give away.

 

[Starrfish]

I have a new alternator that my garage tech says is a match to my old, corroded, no part # alternator. It has the battery post for the red wire and the arm will serve as a ground. It has the connector slot with two little posts that the tech says are for the sensor. He says it will not generate without sensor connected to system. Ok. If I understand the good advice I am getting then I am to find a blue black wire that goes back to the charge lamp and connect it to the two wires that come from the L slot connector I received.

The tech said that one wire from the L connector "may" go to battery terminal and other to idiot light OR "may" need to connect both wires from L connection to the one sensor wire. How do I know?

Back story: I am stranded in a beautiful location off the ICW in Kiawah Island , Charleston. I was motoring back to home port when I noticed my tachometer had died. Keep on to a creek anchorage for the night and noticed cabin lights fading. Next motor no power. Rain and thunderstorms prevented a solar charge so called sea tow for a lift. Be at marina for a week trying to get a re-build then a good guess on a replacement.

Question? I am convinced that I had a one wire system but then what did my tachometer run off of? Any guess at what color the tach wire is? Can I go back with a new alternator to a three wire system?

I am trying to sort out a jumble of wires that have just been hanging without a clear connection to the alternator.

I am going to put in the alternator today and leave the marina if only under two battery power to get to Charleston some 25 nam away.

 

[Scott T-Bird]

I know next to nothing about things electrical but I think I've been able to figure out a few things about wiring. So if you are installing a 3-wire alternator, read the section in the link I provided, it will help understand. The "Batt" connection on the alternator can either be wired directly to your battery, or, more likely it goes to the hot lead on your starter which is right next to your alternator, and is probably how yours is already connected. Either way will work - it's how the alternator feeds the battery.

The "L" can also be wired all the way to your battery (which is the better setup) but can also be just a jumper to the "Batt" connection on the alternator. It is a sensor that senses the voltage at the location it is connected. Either way will work. It is probably easiest right now to wire it as a jumper to the "Batt" post on the alternator. It will get you going and if you want to change it later, you can.

The #1 connector is the source that "excites" the field wiring and it should be wired to the ignition wiring - it's the circuit that tells your alternator to start charging. You'll have to figure out your source for the ignition wiring.

I don't know about the wiring for the tachometer. The tach wasn't working because your alternator stopped charging, I suppose. Remember, the ignition wiring also leads to the starter, which is right next to the alternator, so if you see a lot of wiring in that area, that's because lots of sensors are going to the starter to pick up that ignition current.

HTH ... I got home too late last night to look at my set-up. I pulled my 1GM out 1 year ago and it is in my basement, mounted intact, and waiting for a re-build. I'll try to take a more detailed look tonight.

 

[Steve Dion]

http://www.spidermarine.com/showitem.aspx?&id=100440&name=100%25%20NEW%20Hitachi%20%2012%20Volt%2035%20Amp%20Alternator

I don't know anything about these guys but this will give you an idea of what you are looking for.

 

[kloudie1]

Trying to keep my head straight.. I think the "L" terminal is for LAMP which is the charge light.. The "R" terminal is the sensor wire for the regulator. i just posted the wiring diagram for a three wire alternator on the Yanmar.. Post labeled Yanmar Panel And Harness

 

[Scott T-Bird]

Yes, Kloudie, I believe you are right! I traced the wires back to the control panel (since it is dis-assembled). If he has a 12V 35A Hitachi, the L and R pins are grouped and recessed in the housing. The 2 wires are fitted in a plastic female fitting that slides in. Both wires connect to the cable harness which leads back to the control panel. L was traced back directly to the idiot light, R was traced back to the ignition, which I suppose is the way the sensor is linked to the battery to sense the voltage. On mine, the R wire is red, the L wire is blue. The output wire was jumped to the starter, and finally there is a ground wire jumped to the engine block. That should do it for the alternator.

 

[Scott T-Bird]

Hitachi 12V 35A Alternator

Starrfish, I have my 1GM in the basement so I unraveled the electrical tape which was binding the nest of wires that came together at the wiring harnesses. See if your alternator looks like below. I disconnected the ground at the rusted-looking phillips head connector.