BMW R1200RT/R1250RT Forum

My 3 month old BMW 1250 RT LE came to me with a Denali 120db Soundbomb horn neatly fitted in the steering head position, here's the prob' apparently affecting any BMW with the Canbus system,  here's a quote from A USA forum that describes what happens,  Quote,  "[size=13px]Replaced the stock horn a few months ago with the Denali. Swap was breeze thanks to the picture Brian63 posted.  hit the horn and it stops blaring after maybe 2 seconds and would not sound again until I powered the bike completely off and back on again. Experimented with this many time only to get the same result  I'm assuming it's something with the CANbus not liking the extra electrical pull, but who knows."  [/size][size=13px]Unquote.[/size]


I get exactly the same, horn sounds for 2 secs, cuts off, won't sound again until you switch engine off, restart, will sound again 2 secs and cuts off, this sequence happens every time, further posts on the USA forum state the remedy is to fit a 30 amp mini' relay, (Shows diagram)  anyone else here had any experience of this and /or can recommend a suitable relay  ?
[size=2px]Cheers.[/size][size=13px]

Hi, yes the only way to make it work correctly is to use the original horn loom to trigger the relay and let the relay power the horn.


Quite simple and quick to do as there's loads of space for the relay wiring behind the top fairing panel's

Sorry forgot Durite 0-727-12
12v 30amp is good relay and only cheap

I have a Denali SoundBomb Mini on my other bike and a BMW low-tone car horn on my 1250RT. Both useful improvements.


Now that I have the auxiliary lights on the RT (and the other one) - as well as wearing bright clothing - I find that I have to cover the horn button far less frequently.

You need a relay or otherwise using the horn will trip the Canbus. The horn wire is used to activate the relay. The only way to reset the Canbus is to shut the bike down.
Hornig has a horn kit with the relay and wiring. You can probably make all the parts cheaper but the pics and video on their site can help a lot.
Twin Tone Horn for BMW R 1200 RT, LC (2014-) | Motorcycle Accessory Hornig (motorcycleparts-hornig.com)

Thank you so much michaelc2710 and PatM, your help and advice will enable me to fix my Soundbomb problem.
Cheers guys.