Alarm buzzer never shuts off unless the engine is running!

[Caymus III]

I have a 2002 43' Jeanneau DS. Last fall just before winter layup as I was pulling into my slip the warning buzzer came on. I shut off the engine and the alarm still sounded, it wouldn't stop. At that time I just unplugged the harness from the alarm and figured I'd work on the issue this spring. At first, it was suggested that a new ignition switch was needed. This weekend (June 10, 2018) I decided to look into this issue.
I replaced the ignition switch and the problem still exists. After pulling out the panel and using a voltmeter I discovered that there was a hot lead going to the hour meter connection post on the ignition switch? The former owner stated at time of sale that it had never worked properly and the hours were not accurate. The hot lead was for the kill switch. I moved it to another post. Now the hour meter doesn't run when the engine is not running! However, when I plugged the alarm back in it immediately starts buzzing. When I start the engine - the alarm turns OFF? I have looked at the 3 engine sensors and isolated each one and all 3 are working properly. When I turn the engine off the alarm buzzer goes on! I have also looked at the wiring harness around the port engine mounts as well as up in the trunk and behind the panel. I have a 4JH3E engine and an instrument panel "B".

Any ideas out there with what I can check next?

[mikebnz]

Does it only sound when the key is on? Isn’t that normal? It’s the low oil pressure alarm.
On my DS43 when I turn the key on the alarm starts, then when I start the engine after a few seconds the alarm stops (when the oil pressure rises). When I stop the engine the alarm starts again until I turn off the key.

[Caymus III]

Yes, when I start the engine the alarm goes off.  But when I turn off the engine the alarm turns on, even when I take the key out the alarm stays on.  Is it possible that the alarm can go bad?

Thanks - very perplexed

[rene460]

Hi Caymus, when the key is off, there should be no power to the alarm buzzer, so it sounds like something definitely wrong.

I don't know what documentation you received with your boat, but if you have the Yanmar motor book for your engine, or can find it on the web, or borrow one from somewhere, it has a wiring diagram for each type of engine panel.  That will show you how it is supposed to be wired, and if you follow it through, you may be able to identify whether any obscure fault might power the buzzer when the switch is off.  In a similar way to the obscure earth faults can make your car turning indicators do strange things.  

I don't know why anyone would have modified the wiring, unless at some stage the switch had to be replaced, but it sounds almost like the buzzer power wire has been connected to the wrong side of the switch.  But before disturbing anything, you need the book, and a good look at that wiring diagram.  That wiring is not normally shown in the Jeanneau wiring diagrams.

rene460

[Caymus III]

Thanks very much!  Yes, gremlins are at work here.  Everything was fine and then one day - boom, it started buzzing.  Thanks very much for your feedback.

[Caymus III]

Does anyone have a diagram of the ignition switch? 

[rxc]

I had this problem this past winter, and traced it to a mis-wired (probably by me) lead to my Balmar alternator.I don't know why it started all of a sudden, after 10 years with the alternator, but there is an accessory lead from (somewhere - I am not at the boat and don't have all the drawings at hand) to the voltage regulator on the alternator that had to be removed. Following are several of the drawings I have of various Yanmar engine wiring, including the 4JH3 from around 2002.






I have an engine manual with the key to the various parts in one of the drawings, and will post it when I get back to the boat later in the week, unless someone else has a copy.

[Caymus III]

RXC - Thanks!  Just what I was looking for.