Hi, the buzzer is sounding for the temp overheat right as engine is switched on from cold. On low revs (tick over) it's on constantly, at approx 2700 revs the light just flickers on the panel. Sea water is being pumped through, the expansion tank is the correct level, fresh water is to the top of filler on heat exchanger, raw water impeller is ok. Any ideas"
Yanmar temp buzzer
- Thread starter DJBrookster
- Start date
If you don't find an accidental ground as Stu has mentioned, place an ohmeter across the temperature switch to ground and while in place (wires disconnected) to check the condition of the switch. Should be infinite resistance when cold.
First, check connections at both the senser and buzzer, plus any connections in the wiring between.
Second suspect would be a bad .
Broken wire or a bare spot in the insulation causing a ground somewhere along the line.
Whatever it is, it should be a simple fix.
Second suspect would be a bad .
Broken wire or a bare spot in the insulation causing a ground somewhere along the line.
Whatever it is, it should be a simple fix.
Are you sure the buzzer is indicating high temperature, and not low oil pressure? The oil pressure alarm should come on as soon as the ignition is on, and go off after the pressure comes up. I wonder if the sender for it could've become overly sensitive and so until the RPMs are high enough there's not enough pressure to open that circuit.
From the symptoms described I'm inclined to agree with David that your problem is electrical and coming from the oil pressure side. The pressure switch is pretty easy to check. It is closed (low or no electrical resistance between the terminal and the engine) and only opens when the pressure goes high enough. To test the wiring, just ground the wire to the switch on the engine with the ignition on and the alarm should sound. If the alarm sounds then replace the wire and the alarm should still sound. If not then the switch is bad or has lost its ground due to corrosion. Or you might have a faulty diode in the buzzer. The buzzer has 3 internal diodes, not shown on attached diagram (Yanmar panel type B). If you have a straight shaft, you can try connecting to the red/white wire at the buzzer. That wire if for a sail drive and therefore not used with a straight shaft. Let me know as I might save you time and $$$$ if you find a faulty diode. Good luck
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