NO LUCK WITH HORNS

[jamman18]

I have posted about this before but I'll try picking all of your brains again....

I have a 1977 750 SS and the original horn went out so I got a new one and that one worked for a bit but then stopped.  Ordered another one, got great advise on this forum about wiring up a new one with a new button and that one worked at first too!  Now it doesn't either.  Checked all the wiring with tester and there is no reason why it should not work.  Tried wiring directly to a separate battery and not luck on either of the new ones.  If I didn't know better, I would say they burned out like a lightbulb or something.....strangest thing I seen in a while!

Any advise?

[LukeM]

If you are depending on the horn bracket to supply the ground connection, perhaps something is electrically not all there.  Try running a separate ground wire from the battery or the frame (best bet is to use the GREEN wire from the harness to the frame) to the ground side of the horn (or horn bracket).  Connection should be:
 + side of battery
 to the fuse (if there's one in line)
 to the horn switch
 to one side of the horn
 through the horn (making a beeeep sound)
 to the other side of the horn
 to ground.

I have been reading up on using louder horns, and they use the horn button switch to activate a relay to connect the horns to the battery.  This way, you're not passing 15-20 amps through the horn switch.

I hope this helps.  Keep us in the loop.
Luke M

[TOOLS1]

The horn does not ground through the bracket. They ground through the switch.
Have you tried adjusting the little screw on the horn? Sometimes they will work out of adjustment.
TOOLS

[jamman18]

Everything is wired just as you say and as far as the screw, that is a good idea....the horn slowly slopped working in that at one point I would have to tap it slightly one time and then a bit more the next time before it stopped working.  Thinking there may be something to this screw getting out of adjustment!

Keep you posted!

[jamman18]

Woo hoo!!  I was right in that adjusting the screw out brought the horn back!

[TOOLS1]

Who was right? Glad it worked out.
TOOLS

[jamman18]

Tools gets the prize!!

[jamman18]

I spoke too soon.......attached the horn back on the bike and.....nothing!   Here is how it is wired:



positive battery to fuse to one side of the button to one side of the horn then other side of horn to where the green wire is grounded on the coil.

Suggestions anyone?

[Piute]

[jamman18]

I've got that..........Wiring a new button from scratch so that only does so much good.  I actually need a response more directly toward how I wired it.  Thank you, though!

[sgtslag]

For all things electrical on a bike, check out this book from your local library, or buy it:  link.  The book discusses how to measure voltage drops, and other techniques, to troubleshoot electrical problems.

Now, to your problem.  Does the horn work when directly connected to a 12V battery?  If it does, there is a problem with the wiring on the bike.  Trace the voltage from node, to node [black lead on the (-) battery terminal, moving the red lead], verifying power is reaching the horn.  If you trace 12V all the way to the horn's positive connection, then trace voltage on the ground side, by connecting the positive lead to the (+) connector on the battery, and move the black lead from node to node, on the ground side, verifying voltage at all nodes.  When you fail to read voltage, you have found where the voltage is not reaching -- start there, and work back, to find the open.  Remember that the button has to be closed, for voltage to reach the horn...  Cheers!

[TOOLS1]

jamman18 wrote

I spoke too soon.......attached the horn back on the bike and.....nothing!   Here is how it is wired:



positive battery to fuse to one side of the button to one side of the horn then other side of horn to where the green wire is grounded on the coil.

Suggestions anyone?

THAT'S BACKWARDS!!!!!!!!!!
There is only ONE wire coming from the stock horn button, and it is Light Green.
You run a Black (hot wire) to the horn!!!!! Then you run the Light Green wire from the horn button to the other tab on the horn!!!!!! Then when you press the horn button it makes a ground to complete the circuit!!!!
This is the ? time I have explained this now!!!!
TOOLS

[jamman18]

Thanks for all the tips!  I will keep you all up on the progress!

[jamman18]

A little confused........the way Luke said to wire it in his post above is how I have it and it is not working.  Different from what Tools says........not sure what to think, although Tools is usually correct in his knowledge base.

[Re-run]

OK, do you know if it is the wiring or the horn? It is usually the wiring, especially the button but double check the horn itself. Just hook a couple wires to it and touch it to a battery. Slag mentioned doing this too. If that sucker does not scream from direct voltage, you must somehow keep getting bad horns.

If nothing else, this will point to which spot you need to look.

I didn't fully read everything but at this point, I would just replace all the wires for the horn and replace the switch. It is a simple circuit so it shouldn't be hard to do.
1 question though, which way does the front of your horn face? Obviously forward but is it tilted up or down?

If it is tilted up, it could be catching a lot of road crap that is building up inside. That grud could be causing it to gradually stop working and if you ride in the rain, that water will turn the crap into cement.

The horn should be kinda facing down a bit. I had to replace the horn on my cb years ago and aside from being the typical wimp bike horn, it still works great but it is harder for junk to get into it.

[jamman18]

Ok, how about this way Tools?  What do you think?

[jamman18]

The horn definitely works....it's my wiring...just trying to get a good visual of how to wire it....I'm using all new wiring and button.  See the other schematics I crudely drew,

[TOOLS1]

Your STILL WRONG!!!!!!!!! There is only ONE wire to the switch, and it is the Lite Green one. It goes to the horn from the switch. The other connection on the horn is connected to one of the BLACK (switched hot) wires. The horn button is grounded to the handle bar, and completes the circuit when the button is pressed. The horn itself is NOT grounded! Not even through the bracket, that's why there is rubber in the mount.

TOOLS

[jamman18]

Thank you for the drawing!  Sorry to be so dense....

[jamman18]

One snag with my button though I think.....being an after market switch it just sits velcroed on the handlebar which is why I thought it was not grounded to the handlebar.  I'll try to get a picture to post tomorrow of the setup