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Author Topic:   Alarm Module Mercury 125-HP
seareid posted 05-17-2006 10:21 AM ET (US)   Profile for seareid   Send Email to seareid  
Can anyone tell me where (if?) the alarm module is mounted on a 2003 Mercury 125 Saltwater outboard. I don't seem to have one! Thanks.
Tom W Clark posted 05-17-2006 10:29 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
The alarm module itself is attached to the power head. It is literally a black box. The alarm horn should be somewhere near the helm.

Do not operate your motor until you find it and verify that it is working!

seareid posted 05-17-2006 09:20 PM ET (US)     Profile for seareid  Send Email to seareid     

Thank you. The alarm works when I ground the hi temp sensor. I have to check out the oil level sensor, because it got pretty low, without an alarm. The book shows the wiring from that hi temp sensor and the oil level sw connecting to the alarm module, but on my motor it doesn't. The two sensors are wired together then go back to the horn and ignition sw. I don't think that mine has an alarm module. Does anyone else have this motor? How is it set up? Thanks.

sosmerc posted 05-18-2006 01:14 AM ET (US)     Profile for sosmerc  Send Email to sosmerc     
Yes, Merc decided to save a few bucks and do away with the module. You get no "test beep" when you turn the key on...and now a steady horn can mean either an overheat situation, or just low oil level in the oil tank.
sosmerc posted 05-18-2006 01:21 AM ET (US)     Profile for sosmerc  Send Email to sosmerc     
Seems to me it wouldn't be difficult to add the warning module if you wanted a horn test and descreet warning signals. There's probably still a boss on the lower starboard side of your engine block for mounting the module. The module has two blue wires that connect to the two wires coming out of the bottom of the oil tank, a black ground wire, a purple wire for switched 12 volts positive, and a brown wire that attaches to the terminal block on the engine where the overheat switch lead connects. The last time I checked the modules were about $80.
On the other hand, if you fill your oil tank whenever you gas up, running low on oil should not be an issue. And if you run a temp guage and water pressure guage, you should be able to spot a cooling system problem in the making before getting a warning horn.
seareid posted 05-18-2006 02:58 PM ET (US)     Profile for seareid  Send Email to seareid     
Thanks, Sosmerc. I went down to a Merc dealer today, and he spent a great deal of time looking for a alarm module, to no avail!. The service manager assured us that there was one. It's not listed in the parts or drawings they have. Interestingly, it is in my book, as part of a wiring diagram. Your right, too, as far as a boss. Looks like a bolt hole right were it needs to be! I wouldn't mind hooking one up, just as a form of cheap insurance. Thanks to you both for your input.
umc posted 06-21-2006 10:11 PM ET (US)     Profile for umc  Send Email to umc     
Hello all,

I just purchased a (new to me) boat and it has a 100 horse Merc outboard on it. I've been doing a lot of searching on this sight about the alarm problem I'm having. The previous owner said the random beeping was related to the oil level sensor but never investigated the problem as everything seems to work fine. He just pulled the fuse in the dash to kill the beeping.

I'm not ok with that and have been trying to figure out what is going on. Yesterday I replaced the oil level sensor (and hoses, brittle) but that didn't make a difference. I haven't had it back on the water since our test drive on Monday but when I turn the ignition on I get a steady beep that does not go off.

At this point from my research I think it may be the alarm module or the temp sensor. Before I go out and buy both of these and replace them is there a way to test either item? Is it safe to say that it's one or the other or both at this point? If so should I be fine to run it incase I can't get those parts right away?

Thanks for your time.

Chuck Tribolet posted 06-22-2006 01:04 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
At least on an OMC product, you can test them with an ohmeter.

I'd suggest getting the factory service manual (not Seloc,
and especially not Clymer).


umc posted 06-22-2006 06:42 AM ET (US)     Profile for umc  Send Email to umc     
ok great,

I do plan on getting the service manual and doing a lot of this work myself since the labor rate is 89.00 an hour around here.


jimh posted 06-22-2006 09:21 AM ET (US)     Profile for jimh  Send Email to jimh     
You may find some insight in these articles:

Mercury Oil Injection System

Automatic Oiling System: OMC/Bombardier versus Mercury

particularly the section under the sub-heading Alarm Sensors and System

I an not certain if they are applicable to your vintage of motor, but they may provide some guidance or background for you.

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