Intermittent alarm HELP !

[Joseignacio]

Hello,

I have a 150 HP Mercury outboard 1998 "?ffshore" S/N 0G655314 with carbs. The oil/temp alarm started going off as I was cruising slow at around 3000 RPMs. Since then it will go off as soon as the key is turned one time. Not even with the engine running. I purchased a new Module "41470A23" which was $ 210 and replaced it. Still doing the same thing. Waisted my money. The alarm is intermittent meaning according to the manual that there is an issue with the oil. The oil holder on the front top of the motor is completely full to the top and it even spills when opening the cap. The motor is smoking good when running. The alarm still goes off as soon as the key is turned. Sometimes it will beep as it does when working properly but as soon as the motor starts......there it goes. What else could be wrong? Thanks

 

[j_martin]

Re: Intermittent alarm HELP !

If the alarm goes beep beep beep........... as soon as the key is turned on, and doesn't stop, then the module is bad. Can't be anything else. BTW, a bad battery connection can take the module out in a heartbeat.

Even if either the tank switch or the motion detector were bad, it shouldn't beep more than the 4 or 5 beep power on self test until the engine were started or cranked for several seconds.

If it beeps solid, or maybe changes when you move the steering, then it's wiring or the overheat switch, which is in the same circuit.

Another possibility is if the battery voltage goes too low when cranking, it can drive the oil alert module batty. Likewise if the key switch contacts are bad and the power to it is intermittent, the alarm would likely go off. Come to think of it, I think this is where I'd look first on this one.

Replacing parts without troubleshooting logically to the failed part is the most expensive route to a fix.

hope it helps
John

 

[Joseignacio]

Re: Intermittent alarm HELP !

OK. My key switch looks already old. I was looking to replace the ignition even before this started. Now that you mentioned low voltage, I got a low voltage message while running on my depth finder. Thanks. I will inspect it in the morning.

 

[joed]

Re: Intermittent alarm HELP !

Could be a bad oil tank. Not sure about that engine but some of the engines with oil tanks have a problem with the float. The magnet falls off the bottom of the float and lays in the tank tiggering low oil. If you take the tank off and turn it over and the alarm goes off you know why.

 

[Joseignacio]

Re: Intermittent alarm HELP !

I looked at the ignition switch and the back area where the connections meet, is completely sealed with some type of hard paste. I found another thing today while conducting some more tests. The tan/blue cable coming from the module and connecting to the temp sensor and the horn is sending negative power to the horn and making it go off. I used a volt meter and observed where the tan/blue cable coming from the module is not always sending the same signals. It sometimes send a good signal and the horn will be as before while reseting and before the engine starts. It will be a few times. But sometimes it will just send between 4-5 negative which is enough to make the horn go off. Because of these variations, I believe its the module. The only way that tan/blue cable should have any power going through it, its when a signal from the oil or the temp units send it. I disconnected the temp and still going off. Just the fact that it varies sometimes when the ignition is turned on prior to starting the engine, tells me that the module is not always doing the same thing. please let me know what you think. Thanks.

 

[j_martin]

Re: Intermittent alarm HELP !

I looked at the ignition switch and the back area where the connections meet, is completely sealed with some type of hard paste. I found another thing today while conducting some more tests. The tan/blue cable coming from the module and connecting to the temp sensor and the horn is sending negative power to the horn and making it go off. I used a volt meter and observed where the tan/blue cable coming from the module is not always sending the same signals. It sometimes send a good signal and the horn will be as before while reseting and before the engine starts. It will be a few times. But sometimes it will just send between 4-5 negative which is enough to make the horn go off. Because of these variations, I believe its the module. The only way that tan/blue cable should have any power going through it, its when a signal from the oil or the temp units send it. I disconnected the temp and still going off. Just the fact that it varies sometimes when the ignition is turned on prior to starting the engine, tells me that the module is not always doing the same thing. please let me know what you think. Thanks.

Low voltage or dirty power to the module will do that. So will a short or insulation deterioration anywhere along the tan wire route, including through the controls.

 

[Joseignacio]

Re: Intermittent alarm HELP !

It reads 12.2 Volts. When testing the negative or ground which is the tan/blue from the module, it sometimes read 0 which is good but sometimes there is a leak somewhere and it reads 4 or 5 and the alarm will go off. The ground is what makes the alarm horn to go off. There should be no ground passing through the module unless a sensor (oil/temp) send a ground or negative feed to the module and the module then carries it to the horn. The module is passing ground to the horn most of the time when the ignition key is turned on before starting the engine. Sometimes it will beep normally and shut down when the key is turned on which is the normal operation. But everytime the engine is turned on the alarm will go off. What do you mean by "dirty power"?

 

[jeffersondodson561]

Re: Intermittent alarm HELP !

Float switch? Or if this is the rotational sensor it should be a late model enought to be a single piece pole magnet. Unfortuneately pulling the oil pump will not give you a condition of the worm gear on the crank. So you can either do one of two things (assuming the float switch is not bad). Replace the rotational sensor (magnets very rarely go bad) and hope. If that did not fix it, you can always disconnect the sensor alarm for oil and run premix. But my money is on the float switch. (one way should be 2-6 ohms the other should be OL or OUCH) I always wondered about customer replacing the electronics like you did. I am not comfortable with the phrase their is a sucker born every minute so I always said to them before they bought it "do you wanna see copper turned to gold"? Hey but their is always a learning curve, right?

 

[j_martin]

Re: Intermittent alarm HELP !

It reads 12.2 Volts. When testing the negative or ground which is the tan/blue from the module, it sometimes read 0 which is good but sometimes there is a leak somewhere and it reads 4 or 5 and the alarm will go off. The ground is what makes the alarm horn to go off. There should be no ground passing through the module unless a sensor (oil/temp) send a ground or negative feed to the module and the module then carries it to the horn. The module is passing ground to the horn most of the time when the ignition key is turned on before starting the engine. Sometimes it will beep normally and shut down when the key is turned on which is the normal operation. But everytime the engine is turned on the alarm will go off. What do you mean by "dirty power"?

The control doesn't just pass through a ground from the sensors. It actually has electronics that grounds the tan wire for alarm if conditions, including running status, dictate it.

If you walk up to a boat with a normal system and turn on the key switch, you'll get several beeps of self test, then silence. If you then rapidly turn it off and on a couple of times, the alarm will go crazy. That's dirty power. It can also be caused by a bad connector or a bad ignition switch.

If the instruments are jumpy, that's another indication of bad power.

If the tan wire is accidentally grounded anywhere, it will set off the alarm. The other side of the alarm is wired to switched 12V power.

In the manufacturer's manual there is a complete test sequence for checking out the oil alert system. Get it and use it.

hope it helps
John

 

[Joseignacio]

Re: Intermittent alarm HELP !

Thank you all for your help. It helped me understand more about electrical issues but this time I have to take the boat to a shop. I couldn't find the cause of the alarm.