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04-10-2017 10:02 PM
Re: Yanmar YM oil pressure alarm failure

This reply is too late to help, but someone may read it and find it useful. I have the same problem and the source is the wire connector to the sensor. Over time the wire just corrodes. The simplest way to check is to turn the ignition switch on then, assuming the light and or buzzer aren't working, run a wire from a solid ground (like the battery negative) directly to the sensor and make sure you get a clean connection to where the wire connects to the sensor. If the buzzer works, you need to remove the wire from the sensor, clean the contact and re-attach.
06-27-2013 05:07 PM
Re: Yanmar YM oil pressure alarm failure

The oil pressure sender is located on the engine above the oil filter. It is directly on the block and is slightly below and to the rear of the fuel pump. If you are standing in front of the engine, looking just above the oil filter you should see the wire going to it. If you find it is bad, it is a very simple fix and you should be able to do it in just a few minutes.

You will find the diagrams on page 12 of your owners

Send me a PM if you have further questions.

06-27-2013 04:54 PM
Re: Yanmar YM oil pressure alarm failure

Hi CTLOW---Disconnect wires one at a time and see which light does not go on when you turn switch before starting. Your oil sender will be low on your block, probably just near you fill line or above.
I'm trying to find fittings that go metric 10mm to 1/8 pipe standard so I can put an oil pressure guage on too alongside the sender as I have great pressure but sender goes off sometimes , even after changing !!. I know there was a post re this somewhere ????
07-27-2011 09:18 PM
Yanmar YM oil pressure alarm failure

The latest is that I jiggled everything I could find both on the engine block and on the back of the instrument panel, and nothing worked to restore the alarm.

The next day, however, and ever since, the alarm (and light) has worked. So if I take it in, it will all be working and they won't want to fiddle with it.


Where is the oil pressure sensor on the block, anyway? I can follow all sorts of wires - sort of - but can't convince myself which one is which and can't find a diagram of it. 3YM20.

Thank you.

07-07-2011 07:59 AM
Yanmar YM oil pressure alarm failure

Hello, saillife.

It simply started working again, and I have neglected to check into it. My bad. I had better have a look at the panel wiring - that alarm is a critical component.

Thanks for jogging my memory!

07-06-2011 06:32 PM
saillife Did you have any luck finding your problem? I too have an intermittent problem with the alarm. Mine seems to work once the engine is warm. I'm thinking it's the sender but, it could be heat improving a contact via expansion.
06-11-2011 06:27 AM
ctlow All very helpful. Will investigate and hope to report back. Thanks to all.
06-09-2011 07:50 PM
JimsCAL If you remove the wire from the oil pressure switch and ground it, the alarm should sound (if the key is on). That would test the switch.
06-09-2011 03:18 PM
casey1999 The wire harness have splice connectors- open them up and check for corrosion. Also some of these connectors at the panel. Spray with anti corrosion spray. Trace the wires from the panel to the oil pressure switch- the switch should be located around the oil filter- looks like a 1/2 pipe plug with a wire comming out the top. The water temp switch looks the same but located around the thermostat towards the top of the engine.
06-09-2011 08:50 AM
SVCarolena They way you describe it, it is most likely is a problem in the panel switch. I'd start there with a multimeter before going to the sender. Is is very uncommon for a sender to go bad, particularly on an interment basis like you describe. On the other hand, the panel and switch are exposed to the elements, so there could be corrosion inside.
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