Horn Relay

[Anonymous]

I've almost finished restoring my '79 GS550. The only problem remaining is that the horn's not working. I hear a 'clicking' sound from what appears to be a relay just behind the horns under the front of the gas tank when I press the Horn button.
I'm not much on electrical stuff. Is this a relay & can it go bad? The horn worked when I brought the bike home & I also put the working horn from my Marauder on the GS & it didn't work. Help!!!

[Anonymous]

Relays are usually fitted when someone upgrades the standard useless Jap horn for an aftermarket one that draws more current than the little button on the bars can safely handle.

The relay should be plugged into the wires from the horn button (2 of the 4 pins). If you press the button and hear a click, then the relay would seem to be okay and your problem may lie with the power supply connections to the horn.

There would usually be a fused power supply, either from the battery or from a spare fuse terminal, via the relay to the horn (the other 2 pins). That clicking sound should be the relay switching on this supply when you press the button. The horn itself would usually be earthed to the frame. I'd check the + or earth connections here first for breaks or shortcircuits.

[Anonymous]

So is the relay an original item?
I pulled all the wires, cleaned the terminals with emery cloth, & reconnected. I assume power is getting to the relay or it wouldn't click. I'll have another go at it after work. It's frustrating because everthing else seems to be working OK & I'm clueless when it comes to electrical stuff! And, yes, it's an aftermarket FIAMM horn on the bike, & I would prefer to keep it.

[Anonymous]

No, the relay is not stock. Check that you have voltage coming into the relay (should be a wire going back to the battery). Relay contacts do go bad, but not very often.

[Anonymous]

Actually, the bike had a Vetter Quicksilver fairing (which I removed) and 2 horns, wired together. Is this why the relay was added? I removed one of the horns & attached the wires to the single horn which as I said before, doesn't work. Since I got rid of one of the horns, should I also bypass (and trash) the relay?

[argonsagas]

The relay serves the purpose of allowing a fairly high amperage flow to the horns. The original horns require no relay, so none was installed at the factory. The fact that you have a relay suggests the horns presently on your bike are aftermarket units, which have comparatively high electrical reuirements, and will not work on the original circuit but will likely blow your fuse as soon as you press the horn button.


As already shown above, you must check out the wires to/from the relay and the power source, which is likely a wire direct to the battery, with an in-line fuse attached to it.

The connections at either end of that wire, the fuse, or its holder contacts, may have become dirty and thus do not allow enough electrical flow to meet the needs of your horns, so all you get is a click.

Check the relay voltage input and output with a meter.

[Anonymous]

I know very little about electrical stuff. The relay looked like a factory installation under the front of the tank, so whoever installed it did a good job. There are 3 wires going into the relay (1 green & 1 blue which is split & goes into 2 of the inputs to the relay) & then 2 wires going out to the horn terminals. I guess the relay was installed because 2 horns were installed. The horn itself should be OK as I have the identical horn on my Marauder.
I hope to have it figured out ASAP as everything else is working fine & I want this baby on the road before the weather gets too cold.

[Anonymous]

Cruzuki, the advice you have received here regarding aftermarket horns, higher ampage requirements, the need for a relay in such a situation, and the way to check things out, are all good advice. Let me add that I fitted dual Fiamms to my GS years ago using the relay provided in the kit by Fiamm. However, after a few years the Fiamm relay wore out at the "contact points" and still clicked but did not close the horn circuit. I fitted a standard auto relay as a replacement, which has worked fine since then. I suspect that the problem may lie elsewhere, as indicated by others above, but don't rule out a faulty relay.

Simon Waters

[nabrams]

I spent a lot of time trying to figure out and clean the wiring for the horn of a Honda I had. In the end it was the horn itself that was bad.

I would do the following:

1. Detach the horn from the bike and just run direct wires to a 12V battery to test the horn itself (just close the circuit for a second for the sake of the test). If the horn works, move on to step 2.
2. Remove all the wiring and relay that was set up for this horn and test it against the 12V battery with the horn attached (now that you know the horn is good from step 1). Trace everything to insure that the circuit is being closed - I can't tell you how many times I thought I was making a closed circuit but really wasn't.
3. If it still doesn't work then there's either too much resistance somewhere in the circuit (so the horn can't draw enough current), or the contacts inside the relay just aren't contacting (probably due to dirt).

[Anonymous]

Thanks all for the quick responses. I'll try tonight.

[Anonymous]

Well, I took off the relay & one of the horns. I attached the remaining horn to the wires & Voila! my horn works. I guess the relay was originally installed as part of the dual horn kit after all.
Thanks all for your input.

[mcycle-nut]

It seems his problem is solved, but another thing to check is the horn adjustment if one has a horn that isn't a honkin'! There's an adjustment screw on the horn, which can be adjusted. The easiest way to adjust this is remove the horn, put it in a vise, hook up twelve volts, and start adjusting until one gets a satisfing bleet. Noisy as hell, but it may save buying a horn! 8)