Aftermarket Horn Won't Work

[Guest]

When I bought the bike (81 GS850) last year, the horns were missing. I went to my local motorcycle shop and bought a new, modern horn to use in lieu of the vintage dual horn setup. When I hooked it up and pressed the horn button, all that happened was the lights in the gauges dimmed. I checked the voltage on the orange wire and it read 11.8 volts, roughly. Any ideas on what might be going on here, or a solution to the problem?

Thanks.

[roeme]

Connect the horn directly to a 12 V source (for example, your battery) to rule out a dud. Which is perfectly possible and not unheard (heh) of.

If it doesn't honk, then your contacts must be mightily corroded.

[Steve]

How many electrical terminals are on the horn?

The stock horns have two terminals and are electrically isolated from the frame. One of the terminals is fed by a wire that is always "hot", the other is connected to ground when the horn button is pushed. If your new horn does not have two terminals, a relay can be installed to get it working.

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[PardonMe4687]

Connect the horn directly to a 12 V source (for example, your battery) to rule out a dud. Which is perfectly possible and not unheard (heh) of.

If it doesn't honk, then your contacts must be mightily corroded.

I'll give this a shot, and see if I got a faulty horn. Also, brilliant execution of the art of the pun!

How many electrical terminals are on the horn?

The stock horns have two terminals and are electrically isolated from the frame. One of the terminals is fed by a wire that is always "hot", the other is connected to ground when the horn button is pushed. If your new horn does not have two terminals, a relay can be installed to get it working.

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Steve, the horn has two terminals. I'm assuming the problem either lies with the unit itself, as roeme suggested, or in the ground. However, I did run a wire directly from the horn to the ground connection in the switch and got the same results.

[Steve]

What happens if you connect the horn directly to a battery?

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[PardonMe4687]

What happens if you connect the horn directly to a battery?

.

Been really busy with work lately, and haven't had a chance to check. I'll give this a go tonight, and report my findings.

UPDATE: Horn sounds loud and clear. Looks like I get the opportunity to learn a bit about electrical systems. My plan of action is to isolate both the ground and power wires and check for any visual signs of the problem. If I'm unable to diagnose the issue, I plan to just replace both wires and connections in the loop. Any advise as to a better method, or am I on the right track?

[Steve]

Apparently the new horn has two terminals. See if either one of them is connected to ground (the mounting point for the horn). You can do that by connecting a jumper wire to where you bolt the horn down, then use another jumper wire to touch each of the other terminals. WARNING. If either one of them is connected to ground, your jumper wire will get VERY hot VERY quickly, as it will be a direct short, so just touch the terminals quickly.

If neither one is connected to ground, just connect them to the two terminals that are already on your bike.

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[Cyrano]

I recently replaced the horns on my 850L and needed to wire them in with a relay for them to work properly.

[PardonMe4687]

I recently replaced the horns on my 850L and needed to wire them in with a relay for them to work properly.

What kind of relay, if you don't mind me asking? I'm quite a novice when it comes to electrical work. Thanks.

[posplayr]

What kind of relay, if you don't mind me asking? I'm quite a novice when it comes to electrical work. Thanks.

https://www.thegsresources.com/_forum/showthread.php?154404-FAQ-RELAYS-how-they-work-and-how-to-wire-it-up&highlight=relays