Alarm Buzzer Not Working on Lehman 130

[R. Bush]

I have stopped getting the low oil pressure alarm buzzer when I turn on the ignition. According to my wiring diagram it has to be either a bad connection, a bad relay or a faulty buzzer. How hard can that be to diagnose l asked myself? Except I have looked and looked and can't seem to find either the buzzer or the relay. Can anyone tell me where these parts are usually physically located on an 80s era trawler or even what they look like?

Gotta say that I am feeling pretty stupid having to ask this question!

 

[SIBERNUT]

On my 84 w/ 135, the oil press sender and the alarm sender are next to each other mid height behind the alternator port side. The buzzer is usually close to the helm in the dash or overhead so it can be heard

 

[socalrider]

I have stopped getting the low oil pressure alarm buzzer when I turn on the ignition. According to my wiring diagram it has to be either a bad connection, a bad relay or a faulty buzzer. How hard can that be to diagnose l asked myself? Except I have looked and looked and can't seem to find either the buzzer or the relay. Can anyone tell me where these parts are usually physically located on an 80s era trawler or even what they look like?

Gotta say that I am feeling pretty stupid having to ask this question!

Surprised there's a relay in the circuit - mine just runs right to the buzzer and then to 12V. With no oil pressure, the 12V runs through the buzzer, then to the sender (which is normally closed) and to ground, completing the circuit and sounding the alarm.

Best to start with the oil pressure sender - it should be shorted to ground when the engine is off and there's no oil pressure - just unplug it and do a continuity test from the wire terminal to the sensor body. If that tests correctly you can move up to the relay (if present) and the buzzer itself.

 

[R. Bush]

Surprised there's a relay in the circuit - mine just runs right to the buzzer and then to 12V. With no oil pressure, the 12V runs through the buzzer, then to the sender (which is normally closed) and to ground, completing the circuit and sounding the alarm.

Best to start with the oil pressure sender - it should be shorted to ground when the engine is off and there's no oil pressure - just unplug it and do a continuity test from the wire terminal to the sensor body. If that tests correctly you can move up to the relay (if present) and the buzzer itself.

Thanks for the reply. I started with the engine sensor. It is working correctly. I then followed the blue wire from it which disappeared into a wiring bundle and reemerged in the helm area. From there I tried to locate the relay and the actual buzzer but was unable to find either. Both my son and I looked and looked. I know we must be missing something obvious, but I just can't see what it is.

 

[Choices]

Is your oil prs warning light working?
The relay and buzzer on mine are under the gauges to the right.

 

[socalrider]

My buzzer was a golden colored box around 2”x1”x1” located under my helm station at floor level. But yours could be anywhere!

 

[R. Bush]

Is your oil prs warning light working?
The relay and buzzer on mine are under the gauges to the right.

I don't have an oil pressure warning light - just the buzzer and oil pressure gauge; but the gauge is on a separate circuit.

 

[R. Bush]

My buzzer was a golden colored box around 2”x1”x1” located under my helm station at floor level. But yours could be anywhere!

We didn't see anything like what you are describing. An earlier post suggested that we look behind the panel above the helm at the ceiling. That is the one place we never thought to look so I will check there the next time we are at the boat. At least now I have some idea of what I might be looking for. Thanks.

 

[SoWhat]

Island Gypsy located buzzers inside flybridge compartment, right behind steering wheel.

Very poor location because you can't hear them if running from lower helm with higher rpm. Install relay to connect piezo alarm and red leds. Low oil or high water temps can quickly cause damage.

 

[jleonard]

This diagram shows a relay in the circuit.

 

[R. Bush]

This diagram shows a relay in the circuit.

I couldn't find either the buzzer OR any sigh of a relay. Also; I think the diagram shows the buzzer in the wrong location in the circuit. The way I read it would be that turning on the ignition would cause the alarm to sound continuously.

 

[SoWhat]

I couldn't find either the buzzer OR any sigh of a relay. Also; I think the diagram shows the buzzer in the wrong location in the circuit. The way I read it would be that turning on the ignition would cause the alarm to sound continuously.

New Era HSB relay. 4099 Buzzer below (to the right in photo) Located in my Island Gypsy flybridge. Both parts are still available online.

 

[R. Bush]

New Era HSB relay. 4099 Buzzer below (to the right in photo) Located in my Island Gypsy flybridge. Both parts are still available online.

Found mine exactly where you said they would be. Never occurred to us to look in the flybridge. Looks like the problem is that my relay is shot. Hopefully I can go to an auto supply store and pick up a new one.

Thank you to everyone who took the time to reply. The help is really appreciated.

 

[R. Bush]

Why Is There a Relay?

I got the replacement parts, but am wondering about the installation. In the picture the pink wire comes from the ignition switch and is energized when the switch is turned on. The blue wire comes from the pressure alarm switch on the engine and creates a ground when there is no oil pressure - like at startup. This opens the relay and the brown wire on the right of the relay powers the buzzer. The engine starts, oil pressure rises, and the switch opens breaking the ground connection opening the relay and silencing the alarm.

My question is: Why do I need the relay at all? Why can't I simply connect the pink wire to the positive terminal of the buzzer and the blue wire to the negative?

Am I missing something here?

 

[socalrider]

I got the replacement parts, but am wondering about the installation. In the picture the pink wire comes from the ignition switch and is energized when the switch is turned on. The blue wire comes from the pressure alarm switch on the engine and creates a ground when there is no oil pressure - like at startup. This opens the relay and the brown wire on the right of the relay powers the buzzer. The engine starts, oil pressure rises, and the switch opens breaking the ground connection opening the relay and silencing the alarm.

My question is: Why do I need the relay at all? Why can't I simply connect the pink wire to the positive terminal of the buzzer and the blue wire to the negative?

Am I missing something here?

I'm too lazy to look closely at your wiring, but I suspect that the only reason it makes sense to have a relay in the alarm circuit is that the relay may be energized by a signal from your alternator that the engine is running. This prevents the alarm from sounding when you turn the key to "on", ensuring that your alarm only sounds when the [engine is running] AND [oil pressure low OR temp high]

If you don't care about the alarm going off every time you turn the switch, you can just run it without the relay (that's how mine is wired).

 

[SIBERNUT]

The buzzers on my 1984 Khoudung are next to the stbd wiper motor