Yanmar 1GM10 occasional faint warning alarm / buzzer after start up

[Simon_blackburn]

Good evening, can anyone shed any light on this please? My shipman 28 has a 1GM10 with basic switch panel (key, button, buzzer and three lights).

Every now and again I get a faint beeping (not the usual ear-splitting beep but a much muted version of it) after starting, that revving and / or restarting / turning the key off whilst engine running won’t cure.

Most times it’s silent though.
In the car world there’s a separate lead from the alternator to the dashboard that lights when there’s no charge. However there’s no light and the engine note changes when I switch the charge to the leisure battery.

If it were low oil pressure I would guess that the warning would be much more audible and consistent with revs etc.

I am assuming a short in the switch panel but someone must have had this before? Any advice much appreciated.

 

[LiftyK]

Have you changed the alternator recently?

 

[Simon_blackburn]

No, it’s the original one I think.

 

[VicS]

Good evening, can anyone shed any light on this please? My shipman 28 has a 1GM10 with basic switch panel (key, button, buzzer and three lights).
Every now and again I get a faint beeping (not the usual ear-splitting beep but a much muted version of it) after starting, that revving and / or restarting / turning the key off whilst engine running won’t cure.
Most times it’s silent though.
In the car world there’s a separate lead from the alternator to the dashboard that lights when there’s no charge. However there’s no light and the engine note changes when I switch the charge to the leisure battery.
If it were low oil pressure I would guess that the warning would be much more audible and consistent with revs etc.
I am assuming a short in the switch panel but someone must have had this before? Any advice much appreciated.

the three warning lights are: Ignition/no charge, low oil pressure, and high temperature . Is that correct ? ( on some there is also a saildrive diaphragm failure warning light too.)

When you first switch on the ignition warning light and the low oil pressure warning lights should come on. The buzzer should also sound .... Correct?

When the engine has started the warning lights should go out and the buzzer turn off ..... OK ?

If the oil pressure is low the oil pressure warning light should come on and the buzzer should sound. I will be on or off not variable with rpm.

If the engine overheats the high temperature warning light should come on and the buzzer should sound.

If the charging fails the ignition warning light will come on but the buzzer should not sound

If the buzzer sounds faintly while the engine is running I would suspect that one of the sensors for low oil pressure or high temperature is faulty.

Check by disconnecting them in turn.

There could be a fault ( partial short) in the wiring some where. This will be rather more difficult to trace.

 

[JumbleDuck]

Is it a beeping (ie regular on-off-on-off) or a continuous sign. If the latter, I would investigate the alternator belt. The beginning of a squeal there can sound remarkably electronic.

 

[Simon_blackburn]

Is it a beeping (ie regular on-off-on-off) or a continuous sign. If the latter, I would investigate the alternator belt. The beginning of a squeal there can sound remarkably electronic.

Thanks, it’s definitely the buzzer as covering it up changes the tone! I’m going to try the connections on the engine to start with. Had an overheating problem so I know exactly what that sounds like! Oil pressure even on a failing engine will clear the warning with revs. I think it’s an electrical gremlin. Will report back

 

[Simon_blackburn]

That’s really clear, thanks. And at least I won’t start with the alternator. Will start by cleansing all of the bullet connectors and see if that helps.

 

[VicS]

That’s really clear, thanks. And at least I won’t start with the alternator. Will start by cleansing all of the bullet connectors and see if that helps.

Its always a good idea the clean up connections in this case its not a bad connection that is causing the trouble unless the buzzer does not sound properly when it should sound

 

[Spirit (of Glenans)]

You say there is a change of engine note when you switch to service battery?
This indicates an increase in load on the alternator, similar to when you switch on the a/c in your car when ticking over. I would investigate as to whether there is something shorting and dragging down the charge in your service battery.
You also mention that you switch off the ignition while the engine is running to try to stop the alarm sounding; I'm not sure that's a good idea, it seems to be the common wisdom that that will cause terminal damage to your alternator.

 

[VicS]

You say there is a change of engine note when you switch to service battery?
This indicates an increase in load on the alternator, similar to when you switch on the a/c in your car when ticking over. I would investigate as to whether there is something shorting and dragging down the charge in your service battery.
You also mention that you switch off the ignition while the engine is running to try to stop the alarm sounding; I'm not sure that's a good idea, it seems to be the common wisdom that that will cause terminal damage to your alternator.

Disconnecting the alternator from the battery while it is running is what is likely to blow the diodes in the alternator. Opening the key switch does not do that. OTOH opening the the battery isolator switch will.

HOWEVER

Opening the key switch should turn off the power to the warning lights and buzzer. One would expect it to silence the alarm

 

[Simon_blackburn]

Thanks for all your advice gents. I haven’t had time to investigate in depth but the water into switch via key analysis seemed likely. So I stuffed some winch grease into the key hole when dry: haven’t heard it since.