How should my audible warning system work?

[YN2(SS)]

Ok, as a follow up to a previous thread, I am now working on my audible warning system.

On the engine side, I have a water temp sensor on the port side of the engine and an oil pressure sender on the aft port side of the engine, both wired to the #4 hole on the engine harness plug.

On the boat side harness plug, there is no #4 prong to go into the hole on the engine harness side. However, there is an appropriately colored tan/blue wire that has been run up to the buzzer. The buzzer has a purple and red wire going to it as well. And it looks pretty bad!! Rusty and the like.

So first, when should this buzzer go off? My understanding is when you turn the key to run or start, and the oil pressure is low, then it will alarm. Once the engine is started and oil pressure is good, it goes silent. Then it can come on when the oil pressure drops or water temp gets too high.

How can I test the buzzer now, as well as the sensors. I'll rig a connection at the plug for the engine side to connect to the boat side.

Thanks all!!

 

[YN2(SS)]

Re: How should my audible warning system work?

Sorry guys!

1989 Mercruiser 5.0 LX Alpha One OC507398

 

[achris]

Re: How should my audible warning system work?

In short, the key supplies power to one side of the buzzer, the other side goes to the sensors, which are just switches to ground (as you correctly summized). To test the buzzer, just ground any one of the sensors, or ground the non-power side of the buzzer itself.

Chris.......

 

[YN2(SS)]

Re: How should my audible warning system work?

And answering some of my own questions, I have read through the Merccruiser manual about installing the system as a kit, which I think was done here. I know now that I should be able to turn the key to run, and in 7 to 14 seconds the warning should alarm. But it doesnt. So......

I can check continuity of all the wires easy enough. But how do I test :

The buzzer

the temp sensor

the oil pressure sensor

Thanks all!!

 

[achris]

Re: How should my audible warning system work?

And answering some of my own questions, I have read through the Merccruiser manual about installing the system as a kit, which I think was done here. I know now that I should be able to turn the key to run, and in 7 to 14 seconds the warning should alarm. But it doesnt. So......

I can check continuity of all the wires easy enough. But how do I test :

The buzzer

Answered in the previous reply

the temp sensor

Drop it in boiling water and see if the switch closes. (meter showing a 'short')

the oil pressure sensor

With no oil pressure (ie, engine not running) the switch should be closed (meter shows a 'short')

Chris.....

 

[YN2(SS)]

Re: How should my audible warning system work?

Thanks!!

I'll hit it tomorrow morn!

 

[YN2(SS)]

Re: How should my audible warning system work?

Ok, so I took a multimeter and tested the oil pressure sensor. It was grounded when the engine was not running, not grounded when the engine was running. Good so far!

Then I removed the water temp sensor. No continuity through it! Good! Then I put the tip of the sensor in boiling water, and I had continuity! Even better. So I reinstalled it.

Then I checked the wiring harness and it was in good shape and I added a section to create a quick disconnect at the engine harness plug. I placed the other portion of the quick disconnect on the boat side and checked continuity of the wire all the way to the dash. Good as well. Put it back together, Turned the key and in 10 seconds, I have a buzzer!!! Just like that. Just wasnt connected right. Thanks guys for all your help!!

Onto winterizing the boat!!!