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ContinuousWave: Small Boat Electrical
Interpreting Alarm Cadence of Mercury Outboard
|Author||Topic: Interpreting Alarm Cadence of Mercury Outboard|
posted 04-18-2010 10:44 AM ET (US)
I have a  [Mercury] 150 XR2. When you turn the key [to the ON or RUN position], [the engine] beeps loud[ly] like it[']s suppose[d] to, then, after [the engine] starts there's a continuous low sound beep. All the cylinders don't kick in until a mile of full speed. [The boat is] hard to plane. After a mile, [the engine] runs [well], but the continuous beep still is on.
posted 04-18-2010 12:03 PM ET (US)
Information on how to interpret the meaning of an alarm signal from an outboard motor is usually given in the operating instructions found in the owner's manual. You should consult the owner's manual for your Mercury outboard motor to learn the meaning of a continuous BEEP or alarm sound.
As a general rule, a continuous alarm sound usually indicates an over-heat condition. However, it is not reasonable that the over-heat condition could be present before the engine is even started and the engine is at ambient temperature. In light of this contradiction, there may be something wrong with the alarm system itself.
Problems with the alarm system on Mercury outboard motors creating false alarms are reported quite often. You probably should investigate the alarm system of the motor.
We do not consider troubleshooting the alarm system of an outboard motor to be strictly a small boat electrical problem, and generally the topic is discussed under the REPAIRS/MODS discussion. If you look there you will find in the archives many prior discussions of problems with Mercury alarm systems making BEEP BEEP BEEP warnings or with long BEEEEEEEP tones.
posted 04-18-2010 12:08 PM ET (US)
A good place to begin your reading of article in the REPAIR/MODS archives regarding problems with alarm system on Mercury outboard motors might be
MERCURY Oil Injection Warning System
This search inquiry found many related articles:
Feel free to follow-up in REPAIRS/MODS if you need additional advice on interpretation of the aural alarm from your Mercury motor and diagnostic advice on how to resolve the alarm system problems or the underlying causes of the alarm, if the alarm turns out to be due to a malfunction of one of the monitored systems.
Feel free to follow-up in SMALL BOAT ELECTRICAL if your problem is an electrical problem in your small boat electrical system or in some associated boat electronics, other than the alarm system of your outboard motor.
posted 04-18-2010 12:20 PM ET (US)
Is the engine supposed to beep loudlyt when just turning the ignition key to on? This doesn't happen with my 2000 Merc 75 ELPTO.
posted 04-18-2010 03:00 PM ET (US)
The owner's manual has the answer to what the alarm system is supposed to do when you turn the key from OFF to RUN. In general, most Mercury engine's give an identifying sequence of signals that indicate the alarm system is working and is of a particular type. Again, the owner's manual should explain this. After all, when Mercury made a 1987 motor there was no internet and no forums like this to seek information; you have to assume that Mercury would tell the owner of its motors what those signals mean in their owner's manual literature.
posted 04-18-2010 05:53 PM ET (US)
It would also be helpful if we could get a better description of the alarm. So far we know it is "a low sound." I don't understand exactly what "a low sound" means. Does "low" refer to the pitch of the sound? Does "low" refer to the volume of the sound? If "low" means volume, how is the sound low in volume compared to what? So far the description is a bit nebulous.
If the alarm makes a weak or soft or lower-than-normal volume sound, it could represent just a problem with the alarm itself. Usually these alarm devices are just triggered on or off by the alarm module or the alarm sensors. The sensors do not typically have any way to modulate the volume of the sound or the pitch of the sound from the alarm. So if the alarm begins to make tones that are noticeably different from their normal volume or normal tone, you can suspect that perhaps the alarm itself is having a problem.
posted 04-21-2010 03:58 PM ET (US)
It sounds like the same problem that I had. Try this...while the alarm is sounding unplug the tan signal wire from the back of the alarm module. It should stop beeping. If not the module is shorted internally. I picked one up on ebay for $55.00. Hope this helps......
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