Overheat Warning Horn Sounds Continuously

[Alan Serven]

I have a 1994 Johnson 175 HP 60-degree V-6 that is giving me a continuous warning horn (overheat indication) as soon as the key is turned to the "run" position. This happens even before the engine is started, so I know it is not truly overheated.

Disconnecting leads on the brown wires going to both the port and starboard high temperature sensors does not silence the horn. The engine has a pair of wires (one brown, one black) in a black sleeve coming from the interior of the boat into the engine compartment. Disconnecting THAT brown wire does cause the horn to stop, so the problem (a path to ground) is happening somewhere inside the cowling. I bought a Clymer shop manual for this year/engine, but its wiring diagram conveniently ignores this part of the system, so I don't know what else is in the circuit besides the two overtemp sensors in the heads.

Appreciate any help I can get at this point...
Alan

 

[Tom g]

Re: Overheat Warning Horn Sounds Continuously

you are suppose to get a chirp when you turn the key on, to trouble shoot I would remove the temperature sensor one at a time and see which one is causing the horn to blow. .Grounded somewhere.

 

[Alan Serven]

Re: Overheat Warning Horn Sounds Continuously

As I mentioned in the original post, I have removed both leads to port and starboard sensors and the horn continues to sound.

Some additional information here - the brown and black pair of wires I talk about in the original post (which, when disconnected silence the horn) seem to go to the oil tank level sensor. I topped off the oil tank but this did not help. An ohmeter shows about 2100 ohms across these leads.

Anyone know how to check if this level sensor is good?

 

[ezeke]

Re: Overheat Warning Horn Sounds Continuously

There is a fuel vacuum switch monitoring the fuel supply to the VRO pump.

When it closes, it sends a continuous horn. It tells you that your fuel supply is restricted somewhere before the pump.

The switch is on the "fuel component bracket" on the 150 and 175 and is BRP part #0433409 now superceded by #586544. See # 26 here:

http://epc.brp.com/scripts/EmpartIS...mode=3&cat=25&assem=49676&hideMsg=&imgMap=Yes

And, the bullet leads from the vacuum switch are Tan and Black.

 

[ob]

Re: Overheat Warning Horn Sounds Continuously

Also,try disconnecting the oil reservoir leads and see if it silences the alarm.Recently someone else had the same scenario and that was the culprit.Another possibility is the horn itself.

 

[Alan Serven]

Re: Overheat Warning Horn Sounds Continuously

I did disconnect the leads going to the oil reservoir level sensor and the horn DOES go OFF. So, this means the issue is with the oil level sender??? Oddly enough, this is a replacement (OMC part) as the original failed within the first three weeks of buying the boat back in last 1994.

The thing that has me puzzled is that the low oil level warning is not supposed to be a continuous horn, but that is what I get and what goes away when I disconnect this sensor.

Any idea how to check the oil level sender?

 

[Alan Serven]

Re: Overheat Warning Horn Sounds Continuously

I disconnected the vacuum switch you talked about and it has no effect (the horn conctinues to sound). At this point the only two things that I have found which will stop the horn are:

- Disconnecting either lead (tan or purple) to the horn itself) or,

- Disconnecting the leads going to the oil level sensor

I am strongly suspecting the oil level sender as a result. Any ideas on how to check if it is bad before I just go buy a new one?

Thanks,
Alan

 

[Texasmark]

Re: Overheat Warning Horn Sounds Continuously

As I said in an adjacent post, you should have a warning module that decides what message is sent; intermittent for oil or continuous for overheat. I said that I think that is your problem (the module) and helps to clarify why you are getting confusing information from your sensor troubleshootiing.

Mark

 

[Fl_Richard]

Re: Overheat Warning Horn Sounds Continuously

Not trying to hyjack the thread but ive been looking for a replacement sender for my 3 gallon oil resovoir.(Constant alarm) Any one know what the OEM number is? Seems I can buy the whole tank assembly....

Thanks.

 

[Alan Serven]

Re: Overheat Warning Horn Sounds Continuously

1. To answer the question on the part number; the OMC/Bombardier has the answer - you go to the parts section and navigate to the year and engine type. The oil sender is listed under the "outboard accessories" (or something like that) listing.

2. On my problem, I replaced the oil level sender yesterday and it cleared the warning horn when I turn the key on (now it just "chirps"), now if I can only solve why it is stalling at idle (another thread)...

Thanks for all the help!