Mercruiser alarm

nickmo

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I have a 5.0 mercury engine, alpha 1 gen 2 drive. The alarm will sound for a second or 2 then stop, then a few minutes later sound again. The three issues that will cause an alarm are temp, oil pressure and gear oil. All these are fine when alarm sounds. I'm thinking it's one of the sensors. Is there a way to test them? __________________
 
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I had same intermittent problem for 2 years.I had over tightened battery connections these were the threaded battery posts and over a couple of years those posts broke loose on my battery they are 1 " long stainless with hex end that is incased in lead type material on top of battery .If you have used these try to see if they wiggle with a bit of pressure from pliers .I changed to larger battery posts and problem solved.
 

Fun Times

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Is the engine carbureted or MPI? What year?

If MPI, what is the engine serial number.
 

nickmo

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Could a sticking thermostat cause a slight increase in temp sounding alarm? Temp gauge reads ok.
 

alldodge

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2006 Motor 2 bbl carb.

A 2006 motor with a carb, that sure is puzzling. Is this an older boat with a newer engine?

As FT asked, we sure could sure use the serial number to nail this down. There is another possibility for a constant alarm, that is the seawater pump pressure switch. If you do have obe this is a very common problem. Many can be fixed by removing, cleaning and reinstall, do not use tape or sealant on the threads

Could a sticking thermostat cause a slight increase in temp sounding alarm? Temp gauge reads ok.

No in most all cases, unless your temp switch (not temp sensor) is bad
 
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nickmo

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Yes it's a 2001 with a new crate motor. No computer. From what I understand there are only 3 sensors temp, oil pressure and gear lube.

I'll get a serial # tomorrow. Also, it's not a constant alarm. Thanks.
 

UncleWillie

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... I'm thinking it's one of the sensors. Is there a way to test them?
All three sensors are connected together.
If any one or more close to ground, the alarm sounds.
If the alarm is intermittent but predictable, remove the wire from each sensor (Or all 3!)
With the wire off, the alarm can not sound.
If it still sounds with the wire off, it is not the sensor.
 

camalot

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My guess would be the gear oil senor in the reservoir is stuck to the bottom of the bottle after the gear oil has been changed. Quite common to get a load of slug left and the float will drop and stick to this slug.
 

nickmo

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Thanks, I'm going to remove the wires from all three sensors and run it.
 

nickmo

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I unplugged the three sensors as suggested, started the motor and began running the boat. About a minute later the motor stalled. Started it up and tried again, same thing, I guess there's some sort of safety that shuts the motor down. I plugged them back in and the boat ran fine except for the intermittent alarm. Anyone have a clue what could be causing this?
 

nickmo

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UPDATE

I checked the connection at the ICM as suggested in another thread. I unplugged it and checked the yellow wire. The wire looked fine and there didn't seem to be any corrosion at the plug so I plugged it back in. I had the boat out twice since then and have not heard an alarm yet.
 

Fun Times

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UPDATE

I checked the connection at the ICM as suggested in another thread. I unplugged it and checked the yellow wire. The wire looked fine and there didn't seem to be any corrosion at the plug so I plugged it back in. I had the boat out twice since then and have not heard an alarm yet.
Hum, It's starting to seem like unplugging, checking, cleaning then re-plugging the connector back in is sort of a resetting feature for the TB5 ignition control module when there seems to be a random warning horn alarm on the engine temperature sensor which has a yellow wire going to the ICM as part of the alarm system.

It's an iboats exclusive...:D
 

nickmo

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I want to thank all of you for your help. I've put about 6 hours on the boat and no alarms.
 
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