Yanmar 3YM30 no alarm on key turn

[dave777]

The engine otherwise works OK, and the dashboard lights work. However, there is no audio alarm when the key is put in and turned just before the starter engaged. Likewise after the engine is shut off, there is no audio alarm.

Where should I look first? Where is the alarm speaker/buzzer located?

[sailormed]

Look behind the Yanmar instrument panel. Most probably it is just the buzzer that failed.

[dave777]

Originally Posted by sailormed

Look behind the Yanmar instrument panel. Most probably it is just the buzzer that failed.

That would be wonderful. i'll give it a try.

[Wotname]

You may have a switch on the Yanmar instrument panel that turns off the buzzer. This switch provides the +ve side to the buzzer. It maybe turned off or have failed.

This is fitted to many of the GM series panels but I don't know if it is fitted to the YM series.

[osprey877]

On my engine (not a Yanmar) there is no alarm on key turn if the wire to the oil pressure sensor is disconnected. It is a spade connector and can be accidently pulled off the sensor if you are not careful when mucking about in the engine compartment. The reason the alarm does not sound when the sensor is disconnected is because the pressure sensor is in essence a switch that is closed when there is no oil pressure (which is why the alarm sounds when you first turn the key: the engine is not running, so no oil pressure) and is open (ie no current flows and the alarm stops) once there is sufficient oil pressure. When the oil pressure switch is not connected, there is no current, so there is no alarm. I think most oil pressure sensors work this way. So, check that the oil pressure sensor is properly wired. If you have an oil pressure gauge, not just an alarm, then there should be at least two wires to the sensor, three if you have a dedicated ground (my sensor uses the engine block for the ground, so only two wires: one for the pressure gauge, one for the alarm). Hope that helps.

[clownfishsydney]

Originally Posted by osprey877

On my engine (not a Yanmar) there is no alarm on key turn if the wire to the oil pressure sensor is disconnected. It is a spade connector and can be accidently pulled off the sensor if you are not careful when mucking about in the engine compartment. The reason the alarm does not sound when the sensor is disconnected is because the pressure sensor is in essence a switch that is closed when there is no oil pressure (which is why the alarm sounds when you first turn the key: the engine is not running, so no oil pressure) and is open (ie no current flows and the alarm stops) once there is sufficient oil pressure. When the oil pressure switch is not connected, there is no current, so there is no alarm. I think most oil pressure sensors work this way. So, check that the oil pressure sensor is properly wired. If you have an oil pressure gauge, not just an alarm, then there should be at least two wires to the sensor, three if you have a dedicated ground (my sensor uses the engine block for the ground, so only two wires: one for the pressure gauge, one for the alarm). Hope that helps.

Agree with this, had it happen to us as we were about to cross the Wide Bay Bar in North Queensland. The connector just needed to be squeezed a bit and put back on the engine.

[Hydro2]

Good day, Bearing in mind the key slot is exposed to marine atmosphere, my alarm was intermittent. Inspection on the back side did not reveal anything out of the ordinary. A quick fix for me was spraying a short burst of WD40 into the key slot. The alarm started working every time. Must have been the contacts within the key switch.
Cheers

[dave777]

Thanks for the explanation about the oil sensor.

Looking again at the problem, there are four lights at the top of the engine panel. Only the battery light (alternator charging) turns on now, and there is no alarm. After the engine starts, the battery light goes out.

There used to be two lights that also came on, one is oil and the other is temp or sail drive leak failure.

[Petkal]

Originally Posted by dave777

Thanks for the explanation about the oil sensor.

Looking again at the problem, there are four lights at the top of the engine panel. Only the battery light (alternator charging) turns on now, and there is no alarm. After the engine starts, the battery light goes out.

There used to be two lights that also came on, one is oil and the other is temp or sail drive leak failure.

Hi Dave777

I had exactly the same problem on my 3ym30 engine. First I replaced the circuit with led&bzr ( 129271-91132 ) on my older Yanmar B panel the same as yours. Battery light started on key turn on but no buzzer. Then noticed cable was loose on the oil pressure swith located left on oil filter on motorblock. Thightened wire an put it firmly on oil pressure switch...problem solved!

[RobD527]

how lucky this thread came up, I have the 3ym30 and didn't even think about it that it should have an alarm on startup.

I will dig into it and post my results

[dave777]

Originally Posted by Petkal

Hi Dave777

I had exactly the same problem on my 3ym30 engine. First I replaced the circuit with led&bzr ( 129271-91132 ) on my older Yanmar B panel the same as yours. Battery light started on key turn on but no buzzer. Then noticed cable was loose on the oil pressure swith located left on oil filter on motorblock. Thightened wire an put it firmly on oil pressure switch...problem solved!

Is this the wire for the oil pressure switch? Or is it a ground wire?

After fiddling with the control panel, I examined around the engine again. Examine the the harness connectors, then checked other wires. Turns out that the single wire highlighted in green was the cause, jiggling it got the alarms working again.

Looking inside the jacket of the wire terminal, it looks like it had been crimped. It doesn't fit on snugly anymore. Not sure what to replace it with.

What type of terminal goes here?

[Wotname]

It is the wire for the low oil pressure switch. Yanmar make two types that I have seen. One requires a ring terminal and the other requires a bullet connector (female).

Yours appears to be the bullet connector style.

I have seen others that use a spade terminal but AFAIK, Yanmar does not use them - but I happy to be proved wrong .

The switch connects to ground by the housing of the switch and the engine ground.

[dave777]

The current terminal is intermittent, though it looks (deceptively) good from the outside. With so much continuous vibration on the engine, there'd have to be a pretty solid connection.

I'll need to find a suitable replacement, because on a few hours trip, it could easily dislodge, then I might never hear the engine overheat.

This is the kind of thing I'd pay extra and search for a Yanmar branded part, unless somebody has found a better solution.

[dave777]

Originally Posted by osprey877

On my engine (not a Yanmar) there is no alarm on key turn if the wire to the oil pressure sensor is disconnected. It is a spade connector and can be accidently pulled off the sensor if you are not careful when mucking about in the engine compartment.

That was it! Thank you

[Wotname]

Originally Posted by dave777

The current terminal is intermittent, though it looks (deceptively) good from the outside. With so much continuous vibration on the engine, there'd have to be a pretty solid connection.

I'll need to find a suitable replacement, because on a few hours trip, it could easily dislodge, then I might never hear the engine overheat.

This is the kind of thing I'd pay extra and search for a Yanmar branded part, unless somebody has found a better solution.

Just to be clear, I am almost certain this is the low oil pressure switch and not the coolant temperature overheat switch.