Yanmar instrument panel, strange issues...

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mixmaster

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Our Yanmar 4JH2E has the type B panel I believe (key ignition with a stop button). The first time I tried to start the engine this year, the panel was completely dead. I managed to start it with a switch that I had installed directly on the starter motor years ago.
The panel was still completely dead but when I increased the revs, the tachometer miraculously jumped to life.
I have since been able to start the engine using the key ignition but the stop button has never began working.
I have also noticed that the ignition seems to have a poor connection because when the key is in the "on" position when the engine is off the buzzer works intermittently (you have to fiddle with the key).
I have no idea how raising the revs could have awoken the panel. Also, it seems strange that everything but the stop switch have come back to life. Is the clue in the fact that the ignition key seems to have a poor connection? I should mention that i have been shutting off the engine by pressing on the solenoid directly.

Any clues?

Thank you in advance..
 
mixmaster said:
Our Yanmar 4JH2E has the type B panel I believe (key ignition with a stop button). The first time I tried to start the engine this year, the panel was completely dead. I managed to start it with a switch that I had installed directly on the starter motor years ago.
The panel was still completely dead but when I increased the revs, the tachometer miraculously jumped to life.
I have since been able to start the engine using the key ignition but the stop button has never began working.
I have also noticed that the ignition seems to have a poor connection because when the key is in the "on" position when the engine is off the buzzer works intermittently (you have to fiddle with the key).
I have no idea how raising the revs could have awoken the panel. Also, it seems strange that everything but the stop switch have come back to life. Is the clue in the fact that the ignition key seems to have a poor connection? I should mention that i have been shutting off the engine by pressing on the solenoid directly.

Any clues?

Thank you in advance..
Click to expand...

I think I would suspect the key switch. However it is worth doing some checks before buying a replacement. I don't suppose they are cheap although you may be able to get a suitable substitute from Furneaux Riddall

Check that you have power arriving at the switch . If I have found the right wiring diagram that's the red wire on terminal 30. Check it with a decent sized bulb ( eg head light bulb) on a couple of leads rather than a digital multimeter. They take so little current that they will give a normal readings through poor connections. If you don't have a good power supply suspect the connectors in the wiring harness between panel and engine.

I would not be surprised if there are more bad connections other than a dodgy key switch.
 
I'm not certain that the panel on your engine is the same as the one on mine, 3GM30F, but seems likely. In the cable loom between my panel and engine there are four multi-pin connectors, some wrapped in tape where they are not obvious. After I began to experience engine start problems I disconnected each one and worked them a few times, which fixed the problem. They do seem susceptible to poor connection after a time.
 
Our Yanmar panel is an earlier version, but I dismantled the key switch due to intermittent starting problems. Quite substantial copper wiper parts in the switch - with some corrosion thanks to the marine environment.
Some wet & dry paper and a dose of silicone grease after cleaning solved the issue. (A replacement was £££)
I agree about the multipin connectors- out of sight out of mind and often a source of grief.
 
Apologies for not thanking for all this advice sooner. This gives me plenty to dig into.
Thank you. Will look at connections and check that the key switch is not the issue.
I do find it strange that the stop button is completely dead as well...
Thanks again.
 
mixmaster said:
Apologies for not thanking for all this advice sooner. This gives me plenty to dig into.
Thank you. Will look at connections and check that the key switch is not the issue.
I do find it strange that the stop button is completely dead as well...
Thanks again.
Click to expand...

The stop system operates by applying power to the stop solenoid The power comes via the key switch so if the switch is dicky or if the power supply to the switch is iffy the stop button will be ineffective but there coulld be other issues
 
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This may be of interest. When the key was snapped in my switch by a crew member kicking it (!) on a Sole panel, the price of a "genuine" replacement was ridiculous. I bought a Chinese copy of the Lucas switch, as used on tractors, etc. (under £20) .

Rob.
 
Unfortunately not down on the boat this weekend but I remember that towards the end of last season the alarm would sometimes not activate when the key was in the ON position but the engine off so I'm starting to suspect that it could be the key ignition itself. We'll see and I'll of course report back.
Thanks again.
 
mixmaster said:
Unfortunately not down on the boat this weekend but I remember that towards the end of last season the alarm would sometimes not activate when the key was in the ON position but the engine off so I'm starting to suspect that it could be the key ignition itself. We'll see and I'll of course report back.
Thanks again.
Click to expand...

Could still equally be a dodgy connection in the power supply to the key switch
 
I'm on the boat now and further fiddling with the key switch has led to the stop button coming alive as well! So everything works with exception that the alarm only goes off when key is a very specific "in between" location and this seems to make the stop button work as well.
Has to be the key ignition right?
I have a Yanmar guy showing up tomorrow morning but I think that will be the answer.
 
mixmaster said:
I'm on the boat now and further fiddling with the key switch has led to the stop button coming alive as well! So everything works with exception that the alarm only goes off when key is a very specific "in between" location and this seems to make the stop button work as well.
Has to be the key ignition right?
I have a Yanmar guy showing up tomorrow morning but I think that will be the answer.
Click to expand...

I reckon
 
The most common problem with non-functioning instrument panels is a duff earth connection.
I'm very happy with mine not functioning when I turn on the engine - because once it's started everything, including the warblers, work. It's a 3ym Yanmar.
If you really want to solve the problem, follow VicS suggestion.
I doubt it's the key-switch itself, rather the internal connections.
 
charles_reed said:
The most common problem with non-functioning instrument panels is a duff earth connection.
I'm very happy with mine not functioning when I turn on the engine - because once it's started everything, including the warblers, work. It's a 3ym Yanmar.
If you really want to solve the problem, follow VicS suggestion.
I doubt it's the key-switch itself, rather the internal connections.
Click to expand...

In general a bad negative connection to any panel will affect the operation of the warning buzzer, any illumination and some instruments ( tacho) where applicable, but should not affect the preheating, starting or stopping functions of the key switch.
 
Bumping an old thread, we have a Yanmar 3YM30AE with B20 panel with a push button for power. Yesterday when I push the button, the panel only stayed illuminated with alarms going for a few seconds before shutting down again. If I pressed start within this window, the engine would start and run and all indications normal.

I'm going to pull the panel out and check for good dry connections, but can't find a circuit diagram online for the push button power version, all the downloads I can find have a key switch in the circuit. I wondered how the latching/delay worked on the push button if anyone has a copy of the circuit or link to one?
 
wonkywinch said:
Bumping an old thread, we have a Yanmar 3YM30AE with B20 panel with a push button for power. Yesterday when I push the button, the panel only stayed illuminated with alarms going for a few seconds before shutting down again. If I pressed start within this window, the engine would start and run and all indications normal.

I'm going to pull the panel out and check for good dry connections, but can't find a circuit diagram online for the push button power version, all the downloads I can find have a key switch in the circuit. I wondered how the latching/delay worked on the push button if anyone has a copy of the circuit or link to one?
Click to expand...
That was easy to find , but I am not sure you will find the circuit diagram all that helpful

https://www.yanmar.com/marine/wp-content/uploads/2020/05/0AYMM-EN0028_2019.12.pdf
 
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mixmaster said:
Apologies for not thanking for all this advice sooner. This gives me plenty to dig into.
Thank you. Will look at connections and check that the key switch is not the issue.
I do find it strange that the stop button is completely dead as well...
Thanks again.
Click to expand...
Google search brings up lots of threads re.“Yanmar start problems” mainly down to the light wiring, looms and connectors from switch to starter. Trouble is as it’s intermittent it’s a difficult troubleshoot.
 
Thanks Vic, I'm not convinced the circuit diagram is correct/complete as it's showing a transistor controlled relay on all the other functions but no coil for the power switch relay (I doubt all the panel systems are powered through a transistor). My guess is the detail on part number 18 "control unit/switch module" as it will have current limiting resistors for the other switch circuits and I assume a latching momentary switch circuit (press on/press off) for the power supply.

I'll take it out tomorrow and reverse engineer it.
 
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