Warning Horn Help

[bryan8161]

Took my 1993 Ranger with Johnson 150 Fast Strike to the launch today. While cranking, the engine warning horn started sounding (at the dash console). Stayed on after I started and let run for a minute or so. I have plenty of oil, water running through. This is a solid horn, not intermittent which the manual says overheat. After the boat sets for a while, I can turn the ignition on and just get the test horn and off. However, if I crank it over for 2-3 seconds (without starting, or catching) the alarm horn trips and stays on. The marina's are all 2-3 weeks out and I want to do some spring fishing. Can anyone possibly walk me through this? I am not a mechanic, but I can follow instructions!! Thanks in advance.

 

[GreatDANE]

Re: Warning Horn Help

If u know where the sensor is on your motor first check the wire and make sure that it is not exposed and grounding out, i had a similar problem, but yours chould be more comlicating. some of the more exper. guys will help...
Good luck

 

[bryan8161]

Re: Warning Horn Help

Thanks, but I don't see any problems there. If I am looking at the right area that is.

 

[ezeke]

Re: Warning Horn Help

There are two sources of a constant warning horn on the V6; the overheat switches, and the vacuum switch that lets you know that there is a fuel obstruction on the gasoline side of the fuel pump.

If the constant horn goes off on a cold startup, look for a fuel obstruction.

If the horn is sounding and you want to test the vacuum switch, just undo one of the bullet connectors at the switch.

 

[Brew2]

Re: Warning Horn Help

One other possibility is a faulty sensor. When it happened to me it was a bad sensor in the oil tank resulting in a constant alarm.

To narrow down which sensor is causing the alarm, just follow the tan sensor wires from each possible cause (overheat wire on heads, low oil in oil tank, obstruction in fuel pump) to the connection point and disconnect them one by one until the alarm shuts off. Once you know which sensor is causing the alarm, you can further diagnose why it is happening (fuel obstruction, faulty sensor, grounded wire, faulty horn, etc.).

Good luck.

 

[bryan8161]

Re: Warning Horn Help

I will check the items you have suggested today. Where is the vacuum switch located (thanks for the pic).
Also, the tan wires that go to the heads (heat sensors) I think I looked at them yesterday. There was one tan wire on one side and a white and tan together one the other. these are between the sparkplugs. They go through an opening that looks like a nut. Do I unscrew the nut to get to the leads, or trace the wires back the other way?
One of the replies I got said to check the oil sensor. I assume that is located in the reservoir. In my manual it says that low oil would give an intermittent horn, not constant. Was yours constant when you had this problem?

 

[ezeke]

Re: Warning Horn Help

The tan wires run through all of the warning horn circuits including the oil system and the vacuum switch. There are blocking diodes in the wiring harness to isolate the various signals. The tan wires ground the horn, completing the circuit, when there is a problem.

The vacuum switch is shown with the the normal mounting position denoted by the dotted line to the oil pump bracket, though it could be mounted otherwise.

To eliminate the possibility of the overheat switches causing the problem, they also have quick disconnects in the wiring a few inches from the switches. You usually have to slide a cover back to reach the disconnect.

 

[Brew2]

Re: Warning Horn Help

When my low oil sensor went flakey, it did result in a constant tone. Low oil is supposed to be an intermitent tone, but that assumes the sensor and horn are working properly.

As ezeke pointed out, all the tan wires leading from the various sensors to the warning horn should have a disconnect a few inches from the sensor. Ususally covered by a black rubber sleeve that you have to slide/peel/roll back to expose the connection.

Good luck.