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Author Topic:   OMC Warning Horn
TommyB posted 12-15-2006 01:39 PM ET (US)   Profile for TommyB   Send Email to TommyB  
[Changed TOPIC; was a boat model name and hull dimension. Much later in the discussion the motor involved in this suspected electrical problem was identified as a 1993 Johnson 70-HP outboard--jimh.]

Warning horn sounds continous , according to sticker near key , the problem could be fuel restriction or overheating of the motor . The motor runs fine , but doesnt get up to the 35 Mph that it did before i noticed the waring horn. Thanks any help inadvance. tb

alfa posted 12-15-2006 01:42 PM ET (US)     Profile for alfa  Send Email to alfa     
Seems to be overheating. Confirm via owner's manual. Check cooling circuit. Is the tell tale working ?
TommyB posted 12-15-2006 03:05 PM ET (US)     Profile for TommyB  Send Email to TommyB     

everything is working fine motor runs flawlessly . I called the boston whaler dealer , no real help there . but they seem to think its a number of things sensor or horn. I have all ready figure this much out .
TommyB posted 12-15-2006 03:09 PM ET (US)     Profile for TommyB  Send Email to TommyB     

new to boating , not sure how to check the cooling curcuit. tb

Chuck Tribolet posted 12-15-2006 03:30 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
What motor?

The telltale is a small stream of water coming out of the
the back of the motor that indicates that there's at least
some cooling water circulation. Checking it is the first
thing to do when you suspect an overheat.


davej14 posted 12-15-2006 08:31 PM ET (US)     Profile for davej14  Send Email to davej14     
Does the horn sound continuously when first started?? It would take at least a small amount of time to overheat.
jimh posted 12-15-2006 10:18 PM ET (US)     Profile for jimh  Send Email to jimh     
How can we help you with your boat's electrical system?

We don't really diagnose engine problems here.

TommyB posted 12-16-2006 07:41 AM ET (US)     Profile for TommyB  Send Email to TommyB     

Just trying to see if anyone out there in boat land thought this might be an electrical problem with the horn itself or if it might be a sensor on the motor. Just not sure which way to start to troubleshoot this problem Thanks for all the help .
jimh posted 12-16-2006 08:22 AM ET (US)     Profile for jimh  Send Email to jimh     
It might be a great help if you gave us the information about the model year, the brand, the model, and the horsepower of your motor. This information will help people who are familiar with that particular motor understand the situation.

Many alarm modules sound an alarm on initial power-up as a way of confirming they are working. Your problem may be in that portion of the circuit.

If the warning horn sounds as soon as the ignition switch is turned to the ON or RUN position and the motor has not been running, and the motor is stone-cold, the alarm signal could be false.

TommyB posted 12-16-2006 12:38 PM ET (US)     Profile for TommyB  Send Email to TommyB     

I have a 15' Dauntless Boston Whaler 1993 (I believe that this is the correct year and motor is the same) that has been for the most part in storage in Wisconsin . My step father gave it to me and I brought it here to Florida. The Dauntless has a 70hp Johnson outboard motor with a stainles steel prop, a SST stablizer fin and auto trim tab . I have had this boat since September and have had it in the intercoastal (saltwater) just about every week to go fishing. Not sure what other information I can give you, but thanks again for your help. tb
jimh posted 12-17-2006 10:02 PM ET (US)     Profile for jimh  Send Email to jimh     
If the horn sounds there are several possible causes:

--it has received an alarm signal and sounds a proper alarm
--the horn itself is defective and is sounding a false alarm
--an alarm sensor is defective and is signaling a false alarm

To distinguish between these, temporarily disconnect the alarm signal wire from the alarm itself. This should be a brown wire. If the alarm continues to sound it is probably defective.

If the alarm stops when you disconnect the alarm signal wire, restore the alarm signal wire. Investigate the several sensors to see which one is causing the alarm. You can disconnect them individually. Refer to the engine wiring pictorial diagram at the back of the service manual to locate the alarm sensors and the wiring associated with them. Typically the wire will be color coded with brown insulation. The service manual will give specific instructions on how to test the sensors. For example, the temperature sensor will require you to have a thermometer and an ohmmeter. You heat the sensor to a specified temperature and check to see if it has the proper characteristics. Then you cool it and check for more specific behavior. It is described in the service manual.

If none of the sensors or the alarm itself are defective, you have a valid alarm condition. You will have to investigate the motor itself to see what is causing the alarm condition.

If you want to perform service on your outboard motor, your best investment will be in buying a copy of the factory service manual from your local dealer.

seahorse posted 12-19-2006 07:36 AM ET (US)     Profile for seahorse  Send Email to seahorse     
Your '93 70hp does not have a fuel restriction alarm, that is only on certain V4's and V6's.

IF the alarm sounds after you've been running on plane for a short time, you may have thermostat and spring problems. There were several service bulletins, jet and timing changes (depending on model #) a temp sensor change, an overboard water tell-tale fitting relocation, and a special water pump kit with thermostat springs and tell-tale fittings included back in those years. Some or all may apply to your engine, but you have to have a dealer check old service bulletins for you.

If the horn sounds with the key on and motor off, then you may have a faulty horn, a shorted wire or sensor, or a flakey oil tank pickup assembly. You will need a knowledgeable tech or at least a service manual to troubleshoot.

Be sure that the motor is not overheating first.

On any '95 and earlier OMC engine with alarm problems, the first thing to do is to disconnect the oil tank wires at the motor. The electronics inside the oil pickup assembly can do crazy things and send out weird, erratic, and false warning horn signals.

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