Hopefully some on on here can save me a lot of time and effort, if they have ever had this same problem. Went out to the boat this afternoon, and found the heat/low oil pressure buzzer going off. But only at about half volume. Was on the boat a couple of days ago and it was not doing it then. Double checked, and nothing is turned on, except the auto bilge pump switch. I am reasonably sure it is getting a feedback from somewhere, thus the half volume. But anyone have a guess as to where. The engine is a 3GM Yanmar. 1980 model. Any and all suggestions appreciated.
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Two more of the usual "suspects".....
Agree with C36#2000 (these kinds of number names always evoke pleasant memories of #9 in her Star Trek jumpsuit.....
However, if the alternator diode is OK, try connecting an external ground wire from the panel ground to your negative battery terminal or whatever constitutes your DC ground. If the panel's own ground connection is poor, any leak current could lift it up far enough to make the buzzer (some of which require very little power and are able to operate with reversed polarity)go off. By all means, make sure you do disconnect the shore-power. If you have not already done so, a faulty battery charger would be next on my list of suspects. BTW all of these suspects have been known to be partners in crime as well. Success! Flying Dutchman
Agree with C36#2000 (these kinds of number names always evoke pleasant memories of #9 in her Star Trek jumpsuit.....
However, if the alternator diode is OK, try connecting an external ground wire from the panel ground to your negative battery terminal or whatever constitutes your DC ground. If the panel's own ground connection is poor, any leak current could lift it up far enough to make the buzzer (some of which require very little power and are able to operate with reversed polarity)go off. By all means, make sure you do disconnect the shore-power. If you have not already done so, a faulty battery charger would be next on my list of suspects. BTW all of these suspects have been known to be partners in crime as well. Success! Flying Dutchman
Number of things to check
I am assuming you are hearing the buzzer when the engine is off. Pull the engine panel and with the key in the off position check for 0 v (from battery -) on the switched side of the ignition switch. Also check for low resistance to ground. If that checks out check for voltage on the hot side of of the buzzer and low resistance to ground. You should get 0 volts with the igition off and no circuit in both cases. If that checks out then test for voltage on the ground side of the buzzer. If you get voltage here then one of the ground wires has a short to a power wire and the oil pressure switch is completing the circuit (no engine oil pressure is causing the unit to be closed) The basic technique is to find which side the buzzer is getting power from and ground to and then trace it down the wire till you get to the problem. Almost all buzzers are powered from the ignition switch and are actually turned on by the temp/oil pressure unit completing the circuit to ground. The unit goes to 0 ohms (closes) when oil pressure is low or temp is high.
I am assuming you are hearing the buzzer when the engine is off. Pull the engine panel and with the key in the off position check for 0 v (from battery -) on the switched side of the ignition switch. Also check for low resistance to ground. If that checks out check for voltage on the hot side of of the buzzer and low resistance to ground. You should get 0 volts with the igition off and no circuit in both cases. If that checks out then test for voltage on the ground side of the buzzer. If you get voltage here then one of the ground wires has a short to a power wire and the oil pressure switch is completing the circuit (no engine oil pressure is causing the unit to be closed) The basic technique is to find which side the buzzer is getting power from and ground to and then trace it down the wire till you get to the problem. Almost all buzzers are powered from the ignition switch and are actually turned on by the temp/oil pressure unit completing the circuit to ground. The unit goes to 0 ohms (closes) when oil pressure is low or temp is high.
Thanks
Thanks for the replys. All are very welcome. I must admit that I had not considered the alternator diodes. I have had a couple of issues with ground connections, but only with the anchor and spreader lights. But who knows. Will post up what I find, when I find it.
Thanks for the replys. All are very welcome. I must admit that I had not considered the alternator diodes. I have had a couple of issues with ground connections, but only with the anchor and spreader lights. But who knows. Will post up what I find, when I find it.
Could Be The Engine Harness
If you have a Catalina with the plugs on the end of the engine harness (versus terminal strips) I'd start there. The removeal and replacement of the plugs have been disucssed on many Catalina sites. (i.e. 34 & 36 National Sites, etc.)
If you have a Catalina with the plugs on the end of the engine harness (versus terminal strips) I'd start there. The removeal and replacement of the plugs have been disucssed on many Catalina sites. (i.e. 34 & 36 National Sites, etc.)
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