2003 350 Magnum Bravo3 tach inop and warning alarm beeps every minute

[homelite]

Hello. I bought this boat with a bad engine. I installed a new long block, manifilds, risers, the entire 9 yards. $5500 worth. Did everything right. Started today. Runs great but the tach does not work and Ihave the lettle red alarm beeping every minute while engine is running. I have no idea if the tach worked or not prior. I have my doubts because even though the engine was locked up prior to my being able to actaully run it, when I turned the key on and all the gages powered up, the tacj didn't move. It was resting at 2k and didn't go to zero when the key was turned. It must be getting the signal as the built in digital hour meter works.

As for the little alarm, abviously it gets powered up by the ign being on. The tan/blue wire is controlling it. So....where does this tan/blue wire go and what can trigger this timmed double beep every minute? All other gages are fine as it runs so nothing is wrong.

I'm hoping some expert on this mercury system has some pointers for me.

Thanks in advance.

Scott

 

[spdracr39]

Re: 2003 350 Magnum Bravo3 tach inop and warning alarm beeps every minute

The alarm is tripped by three things. Oil pressure, Engine water temp, And low drive oil in the reservoir.

 

[homelite]

2003 350 Magnum Bravo 3 warning alarm beeps every minute

2003 350 Magnum Bravo 3 warning alarm beeps every minute

Please, I hope someone out there knows exactly how this works and what would cause this. Mine beeps every minute, 2 times. Perfectly timed. Unhook the tan/blue wire from the buzzer and it stops. Ground it and it sounds constantly. My main question is as this tan/blue wire goes through the harness into the engine, where does it go? ECM? How many things trigger it and how does it work? My Seloc manual really doesn't address this. Anyone have the understand of this circuit?

Perhaps with key on, eng off it's supposed to do this?? Perphaps mine is not recognizing the engine is running?? Does it get an oil pressure signal from the ECM? I noticed by the gage sender there is another sender for ECM with 3 wires on it??

I hope someone knows about this circuit and/or this complaint.
I hate to ride with the buzzer unhooked! But now I have to.
Thanks,

 

[Don S]

Re: 2003 350 Magnum Bravo 3 warning alarm beeps every minute

Re: 2003 350 Magnum Bravo 3 warning alarm beeps every minute

The oil pressure, engine temp, and gear lube reservoir all give a steady alarm, and are not your problems. You have EFI problems and need to get it hooked up to a diagnostic computer to find out what is causing the alarm.

Here is a list of the twenty something things that will cause that alarm.

View attachment 555 Audio Alarm chart.pdf

 

[Fun Times]

Re: 2003 350 Magnum Bravo3 tach inop and warning alarm beeps every minute

We'll need the Mercruiser engine serial number if it's available.

Is it EFI, MPI, Or Carbureted?

On the back of the tach there should be a selector switch with an arrow pointing to the numbering system of the engine cylinders, Sometimes it needs to be rotated back and forth a few times then set back into the locking position that matches your engine cylinders. Also try tapping on the gauge.

 

[Don S]

Re: 2003 350 Magnum Bravo3 tach inop and warning alarm beeps every minute

I merged your 2 threads on together. Please don't post the same thing more than once.

 

[homelite]

Re: 2003 350 Magnum Bravo3 tach inop and warning alarm beeps every minute

Can I check for codes without the scan tool? Will a code mater work on my engine. S/n is OM630863. If not, what type of scan tool do I need to buy?

Thank you
Scott