Yanmar 3YM30 where do I find the tacho sensor point?

[Wotname]

Originally Posted by Nautilus2

Aha!!! Did step 1 and tested alternator, fridge, lights, sub etc on. Increased revs in neutral to roughly 2000 by ear. Voltage Stayed at 12.7.

FYI I installed New batteries a few months ago before I left the boat for 3 months. I wired in the new batteries Very Carefully . Boat on the hard. After this, the engine mounts were done by mechanic, boat returned to water, engine good no vibration, and run for a few hours over a three day visit to the nearby Gillis. With solar power, didn’t notice particular lack of battery power, but in hind sight I do recall wondering about the engine running but voltage not reaching the normal 14 pluS. Was on a deadline to return home, left it till my return now to sort out.

So it seems I have been searching in the wrong place, ?

Yes, it seems you have! At 12.7 the alternator is not charging so that = no tacho

Originally Posted by Nautilus2

At the rear of alternator is a two pin I- inset. The cable with the matching pins is not connected. When I connect it and start th engine, the red battery light comes on on panel. I am assuming this is also indicating alternator not charging? I have no idea if this used to be connected before the work was done.

I am happy and grateful for any help you can give me on this, Wotname!

I'm going to assume you have a stock alternator with an internal regulator. If not, only some of the following will be relevant (but who knows which bit ).

So if stock standard, then the two pin T connector should be connected. One of the wires goes to the charge lamp and the other to the internal regulator.

The charge light should illuminate when the key switch is ON before starting and should extinguish after starting indicating the alternator is working. If it stays on after starting, the alternator is mostly like faulty.

[Nautilus2]

Ok thanks for that clarification. Just checking re my reconnection of all the battery terminals. If I had connected something incorrectly, might this be the issue?

[Wotname]

Originally Posted by Nautilus2

Ok thanks for that clarification. Just checking re my reconnection of all the battery terminals. If I had connected something incorrectly, might this be the issue?

Now that is a loaded question

Have you any electrical drawings for the boat or rough hand sketches or similar?

In essence, the output of the alternator (B+ terminal) has to be connected to a battery bank to get any joy and the voltage should be around 14V when the alternator is running.

Can you disconnect the solar panels and/or their regulators while testing the alternator?

Where did you measure the 12.7 V posted earlier - presumably at the battery terminals??

[Nautilus2]

Hi Wotname. Took the measurement straight from the pro star solar charge controller which also gives battery reading.
No wiring diagram for batteries but labelled every cable// wire clearly with battery terminal number etc and reconnected exactly same as far as I know.

I have dragged out the spare brand new alternator that has hardly seen light of day since I bought the boat 5 yeas ago. It looks suspiciously the same in every way- bingo! Thanks to previous owner! Thinking I will get the mechanic back to swap them out- he will be much faster than me and is available. Will soon know if we have to look further for the root problem!

Good idea to make a battery wiring diagram- will do.

I will let you know how it goes. Thanks for everything so far. It’s been really helpful.

[Nautilus2]

Wotname I Also just followed the alternator B+ cable through directly to the batter+. All secure. Can discount that now I think.

[Wotname]

Originally Posted by Nautilus2

Wotname I Also just followed the alternator B+ cable through directly to the batter+. All secure. Can discount that now I think.

Yes I concur although I am assuming this is the same battery bank that the solar panels are connected to.

Is it??

[Nautilus2]

Yes 4 big batteries plus starter bank.
Batteries at 1445 hrs with fridge running are 13.2Attachment 199697

[Nautilus2]

Photo of Battery bank

[Wotname]

Going back to the original problem for a moment - the tacho stopped working after the engine mounts were replaced. A basic tenet of fault finding is to look at the last thing done before the fault appeared. In this case, the replacement of engine mounts would not normally affect the tacho but so far it seems the alternator is suspect. If so, the question is why the alternator has failed and why was the T connector left off.

Your reported tests indicate the alternator is not providing an output voltage but I'm still slightly troubled by subsequent posts. I probably mis-reading them and probably the tests have proved the alternator is faulty.

However please indulge me a moment. After reading the posts below, I still have an uncertainly about your battery setup so a couple more question if I may...

Originally Posted by Nautilus2

Wotname I Also just followed the alternator B+ cable through directly to the batter+. All secure. Can discount that now I think.

Originally Posted by Wotname

Yes I concur although I am assuming this is the same battery bank that the solar panels are connected to.

Is it??

Originally Posted by Nautilus2

Yes 4 big batteries plus starter bank.
Batteries at 1445 hrs with fridge running are 13.2Attachment 199697

So you have 4 big batteries and a starter bank. For ease of writing, let's call the 4 big batteries "the house bank" .

How is the house bank interconnected with the starter bank??

Not at all?
With a switch?
Permanently connected?

What I trying to ascertain is that when you followed the alternator B+ wire to a battery + post, is this post electrically connected to the solar panel regulator that was indicating the 12.7 V noted earlier.

Put another way, was the alternator B+ terminal connected to the same battery bank that was reading 12.7 V.

If so, then yes, the alternator appears to be faulty.

I'm sorry to be so pedantic but I have seen many many installations that aren't logical and therefore owners have difficulty in reporting accurate data because I have made an assumption that their installation is done properly. The devil is always in the detail .

[Nautilus2]

firstly, an update. Yesterday the mechanic and I swapped in the new alternator , and ...nothing different.still no RPM, and battery light\alarm on.
He patiently tested the orange sensor cable through to the display back, cleaned terminals etc. he was methodical and tested/tried every thing he could think of.
Two strange things: the first time with new alternator, we started the engine and had RPMs and alarm lamp/ sound. Stopped engine. He disconnected the T connector and we started a 2 nd time, no RPM and no alarm. reconnected the T connector, No RPM, but needle jumps from below zero to zero when ignition on. All lights on, the off when started, as per normal. Then consistently with further tries, the battery alarm flashes once quickly on//off after starting- hadn’t observed that before.


the pro star smart controller showed batteries at 13.2 . And both home bank and starter battery the same, from solar panels. When engine on, same readings. Also alternator tested showing 13.2. I am confused as to what this tells me, but mechanic seemed sure that the alternator was charging.

I asked to put the batteries under load by turning on the water maker with engine running to observe voltage , and he indulged me. The voltage dropped to 12.5 (fridge was on also). Again not certain what to make of this. I am working with some language and technical barriers here, also , I speak Bahasa but not up with technical terms. At the end of the day, we both agreed that to eliminate concern re alternators, we would get both bench tested this morning hopefully.
One possibility Is both alternators will test ok, then we go from there to solve Tachometer issue.

So, now to your question. I will do my best to answer.
Yes, the BAT+ terminal connects directly to the house bank (at Battery 4+ my numbering system when I put new batteries in).
The solar charge in, is harder for me to trace, but it obviously charges both house bank and starter bank always.
There is a battery isolator switch. Setting 1 draws off starter battery, 2 is house, and also Both and Off. It has since I have owned the boat always been that Off doesn’t appear to turn anything off. I have just lived with it, had a chap who put in a new starter battery at Nongsa 2 years ago check the switch and ascertain the batteries were isolated correctly ie starter 1 and house 2.

Thanks again for your time and patience in providing input into this.

FYI also, the original house bank lasted 9 years, the starter 7 and replaced 2 years ago, then all new batteries 4 months ago, starter was well used in the last few months augmenting the tired house bank.

[rgleason]

Nautilus, I have not read all of this, but does your 3YM30 have a flywheel sensor or not? In my year, 2013, Yanmar dropped the flywheel sensor and used the alternator rotor to sense rpm.

Because my Balmar 90-65 has 13 coils and the original Hitachi 80amp (no external regulator) had 11 coils (I think), and because the adjustment Yanmar provided did not have a stable setting and required a Table to determine the actual rpm, I decided to install a flywheel rpm sensor purchased from Mack Boring (Yanmar).

Perhaps knowing which tach sensing system is used will help determine why it is not working?

[Wotname]

Originally Posted by Nautilus2

firstly, an update. Yesterday the mechanic and I swapped in the new alternator , and ...nothing different.still no RPM, and battery light\alarm on.
He patiently tested the orange sensor cable through to the display back, cleaned terminals etc. he was methodical and tested/tried every thing he could think of.
Two strange things: the first time with new alternator, we started the engine and had RPMs and alarm lamp/ sound.

This is a good sign - suggests the tacho and wiring to the tacho is good!


Stopped engine. He disconnected the T connector and we started a 2 nd time, no RPM and no alarm. reconnected the T connector, No RPM, but needle jumps from below zero to zero when ignition on.

This is bad sign - suggests the problem maybe intermittent - perhaps in the T connector or in the wiring between the T connector and the panel or perhaps inside the alternator.

All lights on, the off when started, as per normal. Then consistently with further tries, the battery alarm flashes once quickly on//off after starting- hadn’t observed that before.

Another possibility is that there is a fault "somewhere" that is killing the alternator(s) - unlikely but possible.

the pro star smart controller showed batteries at 13.2 . And both home bank and starter battery the same, from solar panels. When engine on, same readings. Also alternator tested showing 13.2. I am confused as to what this tells me, but mechanic seemed sure that the alternator was charging.

From what is posted, I think the opposite. It seems like the solar panels/regulator is connected to the batteries as is the alternator. The voltage measured by the solar regulator is will be the highest voltage on the battery. So I'm thinking the solar regulator was delivering 13.2 V to the battery. The alternator should be delivering a higher voltage (say ~14V). However if the alternator is delivering any voltage less than 13.2V, it wouldn't be measured by the solar regulator (while the solar panels are working). So I'm thinking the 13.2V is coming from the solar system and the alternator is producing 0V. Mind you, this is only a best guess from what has been posted and I might be wrong.

I asked to put the batteries under load by turning on the water maker with engine running to observe voltage , and he indulged me. The voltage dropped to 12.5 (fridge was on also). Again not certain what to make of this.

To me, it confirms the alternator is not producing an output. Either because there is a fault (possibility intermittent) in the alternator wiring or the alternator self if faulty. Anytime the alternator is working, the voltage at the batteries connected to it should be say between 13.6V and 14.4V


I am working with some language and technical barriers here, also , I speak Bahasa but not up with technical terms. At the end of the day, we both agreed that to eliminate concern re alternators, we would get both bench tested this morning hopefully.

Sounds like a reasonable way forward!

One possibility Is both alternators will test ok, then we go from there to solve Tachometer issue.

Tentative yes. The alternators may test OK on the bench but unless the wiring is OK in the boat, they still might not work when connected to the boat. However, one step at a time. It will be good to know for sure if they are serviceable or otherwise on the bench.

So, now to your question. I will do my best to answer.
Yes, the BAT+ terminal connects directly to the house bank (at Battery 4+ my numbering system when I put new batteries in).

This is good to know.

The solar charge in, is harder for me to trace, but it obviously charges both house bank and starter bank always.

Let's hope this is true but I get nervous as soon as I hear "obviously". You are likely to be correct but it good practice to prove all assumptions when confronted with a tricky fault.

There is a battery isolator switch. Setting 1 draws off starter battery, 2 is house, and also Both and Off. It has since I have owned the boat always been that Off doesn’t appear to turn anything off. I have just lived with it, had a chap who put in a new starter battery at Nongsa 2 years ago check the switch and ascertain the batteries were isolated correctly ie starter 1 and house 2.

What position is this switch in when you have been doing all the above testing???

Thanks again for your time and patience in providing input into this.

FYI also, the original house bank lasted 9 years, the starter 7 and replaced 2 years ago, then all new batteries 4 months ago, starter was well used in the last few months augmenting the tired house bank.

I hope the above comments make sense and helpful.

[Nautilus2]

Thanks for your interest rgleason , the fly wheel has no electrical connection on it. The engine was installed in MAy 2013, but may not be a 2013 model. The hitachi alternator’ s sensor for tachometer was connected all along, I just didn’t know what I was looking for at the time - actually I was looking for a loose connection somewhere, thinking it had just been knocked during the engine mount work. The replacement alternator is identical, but probably an aftermarket one.

It’s Sunday here, both alternators are being bench tested and I won’t get them back till tomorrow. I will update when I know more. Thanks again.

[Nautilus2]

Hi Wotname, thanks as ever for the detailed feedback points. The alternators are being tested today, and I am hopeful I will see mechanic , alternators, AND his mate the electrician by early afternoon Monday.! Xx fingers.

When I took the 13.2 readings the switch was on 2 ( house bank). Starter battery showed same reading , I assume because the solar panels at midday showing all batteries well charged.

Yes, previously when engine was running (and alternator happily charging) I would observe the voltage to be 14.2.

I meanwhile while waiting, will mull through your points at leisure. Will update when news. Chrs.

[Nautilus2]

Small update Wotname: both alternators bench tested, both found to have “IC terbakar” or a burnt out “IC”. Which my best guess is maybe Internal Contoller”. . Could this be the internal regulator or something in the regulator.? Both repaired and ready to use. So something in the boat wiring is where we need to look?

We had some unexpected weather yesterday so mechanic arrived but anchorage too rolly for mechanic. He should be here this morning. Update later.