BMW R1200RT/R1250RT Forum

Last week I purchased an ex police bike from the police auctions. Does any one know how to fit a horn on a 2014 RTP.


The ex-police bikes do not come with horns as the police use their sirens. So to register the bike for roadworthy purposes, a horn must be fitted. On the previous model, say 2011 or earlier, there was a plug to connect the wiring for the horn. Does not work for the new model. My mechanic said he put the computer on and it says horn deactivated.


Any guidance please.

I'm sure a dealer can reactivate the horn once one is fitted.

Its the independent mechanic asking me, he did all the previous model RTP's for me. Don't want to take it to a dealer, too much $$$.

Heino wrote: Its the independent mechanic asking me, he did all the previous model RTP's for me. Don't want to take it to a dealer, too much $$$.

Unless someone here has a different solution I suspect your solution is only an authorised dealer one.  I suspect all the connections are there for the standard horn so it will only be a plug in to update the software. If the bike has a different canbus loom you have a bit more of a problem.
Just had a look at Real OEM and that shows different wiring harnesses for authority bikes.  If that has an effect on what's there for the ordinary horn I think only BMW can tell you.

Heino wrote: Last week I purchased an ex police bike from the police auctions. Does any one know how to fit a horn on a 2014 RTP.


The ex-police bikes do not come with horns as the police use their sirens. So to register the bike for roadworthy purposes, a horn must be fitted. On the previous model, say 2011 or earlier, there was a plug to connect the wiring for the horn. Does not work for the new model. My mechanic said he put the computer on and it says horn deactivated.


Any guidance please.

All our RTPs have horns as well as sirens. When not riding on blues, you still need a horn

Casbar wrote:
All our RTPs have horns as well as sirens. When not riding on blues, you still need a horn

Except we don't know where in the world he is..  Might make a difference. 

Casbar wrote:
All our RTPs have horns as well as sirens. When not riding on blues, you still need a horn

Is yours a water cooled or air cooled RTP, we haven't a new RTP so don't know how they work as we've gone to Kawasaki but our F800GT is as the poster describes, the horn button operates the sirens with a very loud horn noise, when switched to blues and twos the horn button operates the siren as a siren.

Benchmark wrote: Is yours a water cooled or air cooled RTP, we haven't a new RTP so don't know how they work as we've gone to Kawasaki but our F800GT is as the poster describes, the horn button operates the sirens with a very loud horn noise, when switched to blues and twos the horn button operates the siren as a siren.

Both, but you got me thinking now, because without blues on I have used the horn on its own, it was loud, but I kind of assumed it was the normal horn, but might by out of the siren horns, I'll have to check next time

Casbar wrote:
Both, but you got me thinking now, because without blues on I have used the horn on its own, it was loud, but I kind of assumed it was the normal horn, but might by out of the siren horns, I'll have to check next time

I'm going to guess it does, which is why the original poster can't get the standard horn cable to operate as his bike is still configured as an authority bike and as RTMAN said I bet only a BMW dealer has a chance of setting it back to normal.

Casbar wrote:
Both, but you got me thinking now, because without blues on I have used the horn on its own, it was loud, but I kind of assumed it was the normal horn, but might by out of the siren horns, I'll have to check next time

I've just done a weekend Bloodbike shift on a 2014 RT-P, and used the horn in anger(?) to alert some dozy motorist of my presence. When pressing the horn button, it appears to be a choice (via the buttons E and F (LH cluster, lowest rocker switch), i.e. with E selected, you get a short siren wail when pressing the horn button, or with F selected, you get a short bull horn noise (from the siren). Needless to say, I had the short wail selected and scared the living cr*p out of me and the dozy motorist!!  :alas:

So at the end of the day it's going to take some effort to get it back to the standard squeak.

RTman10 wrote: So at the end of the day it's going to take some effort to get it back to the standard squeak.

It'll be interesting to know the answer before more come back to civvy use, the previous RTP wasn't quite so integrated with the existing switchgear so it wasn't an issue.

Benchmark wrote: It'll be interesting to know the answer before more come back to civvy use, the previous RTP wasn't quite so integrated with the existing switchgear so it wasn't an issue.

Yep, need to check ours, I don't remember a choice, I just pushed and got a horn sound

I am in Melbourne, Australia. The police force here turn over their bikes regularly. I was very lucky to buy a  water-cooled RT (or RTW) with only 5000 km on it.


Anyhow, spoke to the mechanic again today. The readout says "horn disabled" when he plugs the computer into the cluster. This was not the case with previous model RT's. A possibility is to pick up power from the cables as it comes out the horn button, do a relay and add horns. But I will phone the dealer and see if they can assist.


Lastly, police bikes in Aus do not have horns in it.

Heino wrote: I am in Melbourne, Australia. The police force here turn over their bikes regularly. I was very lucky to buy a  water-cooled RT (or RTW) with only 5000 km on it.


Anyhow, spoke to the mechanic again today. The readout says "horn disabled" when he plugs the computer into the cluster. This was not the case with previous model RT's. A possibility is to pick up power from the cables as it comes out the horn button, do a relay and add horns. But I will phone the dealer and see if they can assist.


Lastly, police bikes in Aus do not have horns in it.

Neither do the UK, it's how the current authority bikes are supplied by BMW.

You won't be able to use the horn button as there is no power to or from it, when you get to look at the wiring to the switchgear you will notice there are not enough wires for all the functions, that is because BMW uses a Linbus which sends data to a central controller which turns devices on and off as required.  This is why also there are no fuses as the same controller monitors current draw and if the current exceeds the preset limit for that circuit it automatically turns it off and re-tries the next time the bike is switched on.

So I think you have 2 options.

1. get BMW to re-enable the original horn circuit
2. fit a supplementary switch for the horn