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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 16209
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have a 2007 sea ray with a 4.3L mercruiser sterndrive -

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I have a 2007 sea ray with a 4.3L mercruiser sterndrive - low hours. Continuous horn today - discovered low fluid in gear drive resevoir. filled reservoir, horn still going off.
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so the Marine Mechanic can help you best.
Customer: u have it
JA: Is there anything else important you think the Marine Mechanic should know?
Customer: no

Good morning, my name is ***** ***** am I speaking with? I read what you wrote. Is the engine carbureted or fuel injected? If you have the serial number on it that would be best.

Customer: replied 27 days ago.
Carb. don't have access to the s/n from where i'm at right now. Can I disc the gear drive res wires to confirm that is the problem? Could there be a prob with the sensor?

Okay got it. Does the alarm go off as soon as you start the engine, or only after it has been running for a while? Are there temperature and oil pressure gauges in the boat?

Customer: replied 27 days ago.
s/n 1A047713 Alarm stays on when the engine is started. Have temp gauge but it reads cool on start up - normally is at 170 when warmed up. Oil pressure reads normal.

Got it. There are 3 things that will cause the alarm to go off on this engine.

1. Low gear lube, or a bad gear lube sensor in the bottle.

2. Engine overheat or a bad temperature switch.

3. Low oil pressure, or a bad oil pressure switch.

The gear lube sensor is in the bottom of the bottle. The temperature switch is at the thermostat housing. The oil pressure switch is located down near the oil filter. The wire colors for the oil pressure switch and the gear lube are tan with a blue stripe. The wire color for a temperature switch is yellow. All you would need to do is start the engine up, duplicate the alarm, and then when the alarm is going off simply disconnect each of those 3 sensors. Whichever one silences the alarm is going to be the bad sensor. Does that all make sense. That is where you stand on your end and what the problem is. I think that should do it but I work for tips so I do want to make sure you are happy with my service before you go. If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Please note that our question sessions never close out, so if you need to come back later down the road with follow up questions to the issue, you can do so at any time, even after putting through a rating.

Thanks in advance, and good luck

Customer: replied 27 days ago.
OK - thanks. I'm going to check it out tonite. If I confirm it is the gear drive sensor problem and given the reservoir is full, can I leave the wires disconnected (to silence the alarm) and run the boat until I have the sensor replaced in a couple weeks?

If I confirm it is the gear drive sensor problem and given the reservoir is full, can I leave the wires disconnected (to silence the alarm) and run the boat until I have the sensor replaced in a couple weeks? ​

​You can do that with all 3 of the switches. That being said the way the alarm is supposed to work is the drive gear switch would cause a beeping over and over, the oil and temp switches would cause a constant alarm. So as long as your alarm is acting properly it wouldn't be the gear lube switch causing the problem, it would be one of the other two.

Customer: replied 27 days ago.
Hmmm - that's odd given I don't think I ever heard any beeping, just the constant alarm. Hard to believe its a temp issue given it is alarming at start up on a cool engine. Oil gauge is reading right in the middle, oil level is good. Possible that there is something going on with the oil pressure.

The engine has an alarm switch for the gear lube. It also has alarm switches for both the temperature and oil pressure. These are switches, and they are for the alarm only. The engine also has what are called sending units. These sending units send are what send a signal to your oil pressure and temp gauges. These work independently of the gauges. Either switch (temp or oil pressure) if bad will normally sound a constant alarm. The gear lube switch when bad will sound a beeping over and over. So that temp switch can definitely be bad and sounding the alarm on a cold engine. (happens all the time).

Jason and 2 other Boat Specialists are ready to help you
Customer: replied 27 days ago.
ok - thanks.

You are very welcome. Thanks again and happy boating! -Jason

Customer: replied 26 days ago.
Jason - matt here. I could use a little more input. I found all 3 wires you reference above. To be clear, I'm working on the wires around the engine. With the engine running, I disconnected the quick disconnect coupler for each of the 3: gear lube, oil pressure and temp. I could not get the audible alarm to stop when I disconnected the wires for each area. I'm assuming I'm not doing something properly - any thoughts? Thanks.

Hi Matt. You should have a tan/blue and black wire at the gear lube switch, a tan/blue at the oil pressure switch, and finally a yellow at the temperature switch. Do you have all 4 of those wires disconnected?

Customer: replied 25 days ago.
Not all at the same time.

Pull them all off and see what happens.

Customer: replied 25 days ago.
ok - I'll try it tomorrow morning. Thanks for your patience - I'll definitely send u a tip if you can help me get this figured out.

No problem, there are no time limits here.

Customer: replied 24 days ago.
Pulled all 3 disconnect couplers: 1 - yellow, 2 - tan with blue stripe. Alarm did not go off. There was another coupler fed from underneath the air filter - that one killed the engine.

W​hen you say the alarm did not go off do you mean that the alarm did not stop going off (it was beeping) , or the alarm did not come on at all? (alarm was silent)

Customer: replied 24 days ago.
I started the engine - alarm continuous horn, pulled all 3 couplers - still continuous horn. There is another coupler next to the gear lube coupler - pulled that and it has a clip fuse inside, pulled the fuse - horn still going off continuous. I think the only thing different on the wire colors is the gear lube at the coupler is tan/blue and white, not tan/blue and black.
Customer: replied 24 days ago.
My bad - that early reply was not worded well.
Customer: replied 24 days ago.
My wife was operating the boat when this started. She turned the engine on like normal and was backing out of our slip, she said the throttle was a little high because the throttle is touchy but nothing off the charts. Alarm started sounding continuous at that point. she drove it back on the lift and that is where it has sat. I found the gear lube reservoir almost empty (to the sensor) so I assumed that was the issue but then you are saying that should of only caused a beeping alarm. We've never had a beeping alarm occur.
Customer: replied 24 days ago.
whats it run for a phone call?
Customer: replied 24 days ago.
This engine has extremely low hours (188) - the previous owner apparently took it out once a year for a ride around the lake and then parked it. I've had it for 2 seasons and put 170 miles on with no issues until now.
Customer: replied 24 days ago.
170 hours

The phone call is an additional 26. I am available for a call at the moment, but will not be later on. There is going to be a temperature sending unit located right near where the temp switch was located. This temp sending unit will have a either a tan or a tan with a blue wire on it. Just for the heck of it, disconnect this wire and let me know if the alarm still sounds or if it goes silent.

Customer: replied 24 days ago.
ok - sorry, ran out of time. I'll try it after work tomorrow. Thanks.

No problem, just reply back tomorrow. We'll get this sorted out and try and save you a trip to the dealer.

Customer: replied 23 days ago.
I disconnected the tan wire going to the sending unit for the temp. Horn still sounds.
Customer: replied 23 days ago.
pulled the tan wire going to the temp sending unit and the horn is still on.

Good morning. Are you positive the alarm is engine alarm that is going off? Do you have anything else in the boat, like a depth finder, or some kind of fuel/CO detector that also has an alarm?

Customer: replied 23 days ago.
depth finder but this is the same horn/alarm that goes on when you first turn the key over - it just stays on after the engine starts. I'll investigate the death finder.

Do you know how to read a wiring diagram if I upload one for you?

Customer: replied 23 days ago.
I'll give it a shot.

Okay i'm uploading it now. Let me know when you can see it.

Customer: replied 22 days ago.
ok - sorry, work got in the way. I've printed the schematic and am looking at it.

The way the alarm system works is the buzzer itself has a positive and negative terminal. Power to the buzzer is provided by the key switch. Ground for the alarm is provided by the alarm system. If you look at the diagram you want to look at block C on page 2. Block C contains the gear lube sensor. The oil pressure sensor. And the temp sensor. If you look at the diagram. Ground for the buzzer on the gear lube sensor and the oil pressure sensor is provided directly by those sensors. The ground wire is that tan/blue wire. On the water temp sensor. That wire is yellow. If you look at the diagram carefully you will see that the yellow wire runs over to the ignition module on the distributor. Then leaving that same module is another tan/blue that connects to the same spot as the gear lube and oil pressure sensors. The way the system normally works is if the oil pressure or gear lube sensors activate, those sensors directly ground the buzzer completing the circuit. If the temp sensor activates, that sends a signal over to the ignition module, the module in turn grounds out that tan/blue wire, completing the circuit and sounding the alarm. 99% of the time whenever you have an alarm as soon as you start the engine up, it's one of those 3 sensors that is bad. Unfortunately your engine is in the remaining 1%, where the problem isn't one of those 3 sensors. Instead, you either have a bad ignition module. A shorted yellow wire between the temp sensor and ignition module. A bad ignition module. Or a short in the tan/blue wire someplace on the engine.

So your next steps would be to

1. Cut the yellow wire at the ignition module and see if the alarm stops or not. If it does, that wire is shorted someplace on the engine. Obviously leave yourself enough wire to splice the 2 back together when you are done. If that does not stop the alarm then;

2. Cut the tan/blue wire at the ignition module. If the alarm stops. The ignition module is actually bad, and grounding that tan/blue wire with no input from the yellow wire. If the alarm continues with this wire cut. Then there is s short circuit someplace on the engine on that tan/blue wire, and the wire is grounding out someplace on the engine block. There is no real way to find a short like this without tearing everything apart so the simpliest thing here would be to rewire the alarm circuits from scratch.