stumped on wiring and horn.

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I have a 2005 abs ST1300 and the horn has stopped working. Its a Stebel and I took it off, ran power to it from a separate battery and it works. I changed the connectors on the wiring connecting power to the horn, didn't work.
The relay is clicking when I turn on the key and push the horn button, but I don't seem to be getting power to the horn itself.I'm assuming the relay works because its clicking, is this correct? I also have clearwater lights hooked into the horn wire that goes into the relay and horn that flash the lights to full power when the horn is honked. I assumed that the horn switch was okay beings that the flashing lights function works.
Is that assumption incorrect ? I'm pretty ignorant with electronics but learning. slowly.
I have a multi meter but don't know how to test the wiring to see where the power is deficient.
I can take pictures if it helps show what I'm talking about.
 
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If there is power to the horn, and the horn isnt faulty as you have checked it, then the ground must not be good, or there is not 12 volts going to the horn from the relay. Test the wire that goes to the horn with your mutlimeter for voltage as the horn button is pushed. If around 12 volts, take another wire and ground your horn to the frame to try to ground it better. See what you get. Its hard to tell but I am guessing ground without seeing it.
 

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A note on Stebels - If water gets into the trumpet, the compressor will spin up but the horn will not make a sound (and the trumpet is toast). I've had several Stebels do this so I switched to Fiamm Highway Blasters. You should be able to put your hand on the compressor part and feel some vibration when you press the button if it is working. If it is a standard relay, a simple test light will allow you to test it. Test your 'hot' in and your 'hot' out when you activate it.
 

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I changed the connectors on the wiring connecting power to the horn, didn't work.
First things first: when you're trying to diagnose a problem, don't add variables by changing things you haven't determined to be a problem.

I'm assuming the relay works because its clicking, is this correct?
Nope, not a valid assumption. Relays are mechanical devices (see video below) that can fail. The clicking you hear just means that part of it is being pulled in and hitting something; it does not guarantee that the circuit it switches is being completed. Check this by making sure the voltage you're switching is present on one contact when the relay isn't energized and becomes available on the other when it is.


You've already determined that the horn itself isn't the cause. What you need to do is trace both ends of the circuit back to the battery, making sure there's DC in the right places each step of the way. Once you've done that for the positive side, you can investigate the negative side.

--Mark

https://www.youtube.com/watch?v=kt-4jJvYvzI
 

ibike2havefun

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Thinking about what you describe points me in the direction of the ground from the horn, especially if it is not the same as the ground from the extra lights. Trace that wire and check its connections.

You can check the continuity with your multi meter, too. Put it in ohms mode, and touch one lead at the horn end, the other at the far end of the ground wire. Should read a low number.

You can also check by touching some other ground point. If the horn ground is good you should get a similar reading.

Touching the leads to the connections on the Stebel itself will tell you whether it has a problem. Expect a number higher than checking the ground wire itself, but still only a few ohms.
 
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I also have clearwater lights hooked into the horn wire that goes into the relay and horn that flash the lights to full power when the horn is honked. I assumed that the horn switch was okay beings that the flashing lights function works.
This is a little hard to understand, but I'm assuming the lights are on the 'load' side of the relay, along with the horn?

If both the lights and horn are on the load side, then there are two possibilities. The first is as others have said, you lost your ground connection for the horn so the circuit is broken. If you can disconnect the horn wire on the ground side and touch it to the engine or other frame ground point the horn should work. That's probably the most likely cause, so once you can identify that's the problem you can then work on reconnecting the original wire and figure out why your ground point is floating.

Another possibility is your relay load side has developed internal corrosion and is creating a voltage drop across the corrosion. If the lights are a low current draw, like LEDs, they can operate OK because the low current doesn't create much voltage drop. But when you add in the current load of the horn the voltage drops to a level that's too low to operate the horn. If your lights are a high current draw like quartz-halogen, then this is far less likely to be the case. One way to rule this out is to check the voltage between the horn connection on the relay to ground. If that connection shows ~12v and the horn isn't working, then its back to the ground problem. If that connection is a lower voltage, then measure the voltage drop across the relay load terminals (if possible), it should be fairly low, like a volt or less but I can't give you an exact figure.
 
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I have a multi meter but don't know how to test the wiring to see where the power is deficient.
ibiketohavefun suggested using your multimeter on ohms. Make sure that what you are testing has NO voltage.
More expensive multimeters have a fuse in the circuit inside the meter when set to test ohms, cheap ones do not. If you test 12v with a meter set to test resistance you stand a good chance of frying the meter (or blowing the fuse).
 
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It states added battery power to horn and it works.. that eliminates a bad ground. States horn is also hooked to same relay as lights, lights flash, that eliminates relay unless voltage is low. Put a volt meter on the b+ horn wire and should be battery voltage (which were are sure there is none or is low), if not check battery voltage at 87a and 30 on relay. (button pushed) 12v is on battery side and 12v on relay side. If voltage is good its a wire or connector to the horn. If battery volts are low to the relay check that wire or connectors, voltage good at relay but not out= bad relay. all we need to check for is voltage and where it stops. simple
 

ibike2havefun

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ibiketohavefun suggested using your multimeter on ohms. Make sure that what you are testing has NO voltage. More expensive multimeters have a fuse in the circuit inside the meter when set to test ohms, cheap ones do not. If you test 12v with a meter set to test resistance you stand a good chance of frying the meter (or blowing the fuse).
Good point. I was assuming the test conditions to be:

*Ignition off
*Horn button not pressed, so horn relay not activated and circuit open
*Checking ground side of load only, so no voltage.

Good to clarify that.
 
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THANKS a bunch for all the suggestions!
As suggested I ran a wire from the negative on the horn itself to the frame and connected power as normal from the relay to the horn. It honked as its supposed to.
There is a ground wire from the battery negative that goes straight to the horn. The power runs from the battery to a fuse then to the front into a relay, then out from there into the horn. I ran a wire from negative on the horn to neg on the battery and it honked just fine.

I'm going to pull the negative wire from the battery to horn and check it for breaks or inconsistencies, but have a limited amount of time off here from my stay at home dad day job and would like to do that when I get back from my trip.

Is it okay to just run another wire from ground on the battery or on the frame up front into the horn mimicking whats there? That sounds like a dumb question but I'm trying to get out of town and would leave the current ground wire there until I get back and take it out properly.

I tested 87 and 30 at first both were 12v. I ordered a new relay of the same type which will get here Tuesday just on the chance there is some corrosion, its less than $10.
 
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THANKS a bunch for all the suggestions!
As suggested I ran a wire from the negative on the horn itself to the frame and connected power as normal from the relay to the horn. It honked as its supposed to.
There is a ground wire from the battery negative that goes straight to the horn. The power runs from the battery to a fuse then to the front into a relay, then out from there into the horn. I ran a wire from negative on the horn to neg on the battery and it honked just fine.

I'm going to pull the negative wire from the battery to horn and check it for breaks or inconsistencies, but have a limited amount of time off here from my stay at home dad day job and would like to do that when I get back from my trip.

Is it okay to just run another wire from ground on the battery or on the frame up front into the horn mimicking whats there? That sounds like a dumb question but I'm trying to get out of town and would leave the current ground wire there until I get back and take it out properly.
Sure you can. Either run the wire to the frame or to the battery neg (they are electrically identical - or at least should be at the same potential (voltage)). Remove the other one later so you don't end up w/ unused wires confusing the issue.
 

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You may want to determine if your relay is sealed or not. Sealed relays tend to last longer and resist corrosion better.
 
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rdmsttrav
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DOH!
So after all that I decided to recheck everything.
What I Thought was the ground wire to the battery from the horn was not. I traced the wire and where I thought it stayed in a nicely covered line to the battery, it didn't. I used fingers on instead of sight and found it cut out of its covering and was an unattached ground wire floating around. It had come out of its attachment.
I reattached it and the horn works just fine.
When I thought I checked the simple thing I wasn't checking the right wire. I'm embarrassed but equally happy I don't have to rewire anything or replace anything.

Thanks again for all the help.
 
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