12V Safety Horn not working although it receives 12V.

[cprodave]

My safety/drivers horn doesn't work when I toggle the horn switch on my Seapro 2001 18ft Center Console. Measured with DC Voltmeter clipped on at the 2 plugs/connectors which go onto the horn, I get 12VDC "steady" when I toggle-on the Horn. But when I plug in the horn, I get only a quick buzz out of the horn, not really a horn sound, only momentarily buzz or click like something is attempting to actuate. I have tried both the original horn (15years old) plus a brand new horn, with same result. I also tested each horn by connecting to my 12V battery directly, and each horn works fine.

What the heck is going on here??? Please help! Thanks in advance...

 

[Scott Danforth]

You have a bad/corroded connection somewhere along the circuit

 

[cprodave]

Scott, thanks for the input. I will look for a bad/corroded connection. It seems weird though that I am reading 12Volts steady at those connectors. Does a horn draw a lot of current, similar to how the engine starter wires/connection on the battery need to be "squeaky clean, bright and tight"?

 

[Scott Danforth]

you can have 12 volts with a meter, however as soon as you put any load, its gone because of a corroded connection. you should also be using a test light

most horns draw about 6 amps

 

[fhhuber]

Put voltmeter across the horn and watch the voltage when you depress the horn button. Compare with the reading when the horn will work properly. It will be significantly less when it does not work, due to resistance between the horn and the battery.

The resistance might be wire that is corroding inside the insulation or bad connections or someone replaced the horn wires with too light a gauge... whatever.

 

[cprodave]

Update: I had changed the ground connector prior to my last post because it looked bad/corroded. The positive connector looked good. However, base on forum inputs, I proceeded to change the positive connector too. Now the old horn works, although a little weak. The new horn doesn't work at all (it probably draws more current). I will keep looking for aged/corroded connectors (and any undersize wires) to get this problem 100% resolved. Thanks for all your inputs.

 

[GA_Boater]

One often overlooked source of a voltage drop is fuses. Overlooked because you find 12 volts out of the fuse, so it must be good. Ends on tubular fuses and blades on the flat type, corrode and the holders as well. One more thing to check.

 

[cprodave]

GA Boater, thanks for the input, I will check the only fuse that exists on this circuit and will advise back on this forum.

 

[gm280]

If you checked all connections and it still is weak, time to replace the old wire. It is not allowing the current to flow and that could be corroded wire inside the insulation somewhere on the wire run. And don't just replace the positive wire run. Replace both positive and negative wires. And that is because the same current has to be able to flow through both wires for it to work. So many times people neglect the ground wire runs. JMHO

 

[fhhuber]

If you checked all connections and it still is weak, time to replace the old wire. It is not allowing the current to flow and that could be corroded wire inside the insulation somewhere on the wire run. And don't just replace the positive wire run. Replace both positive and negative wires. And that is because the same current has to be able to flow through both wires for it to work. So many times people neglect the ground wire runs. JMHO

And... use marine grade wire or it will corrode quickly and need replacement again.

 

[cprodave]

Thanks to all for additional input, I will check (and replace as necessary) the black wire too.