RTP batteries & horn issues

[Tschamp]

Is it common for the RTP's horn not to be working?

Can you replace horn without taking fairing off?

Should the batteries be tied together?

[TMH]

Is it common for the RTP's horn not to be working? Not that I've heard of. Mine works fine. Perhaps the dept which had yours in service disconnected it because they had other means of audible signalling?

Can you replace horn without taking fairing off? Are you sure you need to do that? Have you checked whether the horn relay in the fusebox is clicking when you push the switch? Is it even there?

Should the batteries be tied together? The batteries on mine are separate: I have to use 2 trickle chargers accessing the front (aux) battery from the power outlet on the dash, and the rear (main) battery from the power outlet below and left side of the seat.

 

Tom

[celebrationrev]

Can't comment on the second two, but my horn did not work when I got my bike. Neither did the parking lights. I took it back and they chased out the wiring issues and restored both. Apparently the CHP (or other) disconnects the horn to use that switch for other things. And when you think about it, they have plenty of ways to make noise without BMW's horn.

[Tschamp]

Yes, I do hear the relay click, it also dims the headlight a little and will blow the turn signal fuse, if they are on when trying to use the horn.

The front battery has not positive lead attached, only negative.

[TMH]

I think that you can get to the horn (electrical) connection by just reaching up or down into the space in the front. I would try to disconnect the wire from the horn, and see if it still does what you say. If so, then there may be a short somewhere in the wiring. If not, then it does sound like your horn unit is bad and is internally shorting.

 

Do you still have the front crash bars on your bike? If you don't mind the look, you can mount 2 horns, one on each side. Jeff Dean has done this with his bike, and used horns that folks in cars can actually hear. Check out this link:

http://jeff.dean.home.att.net/horns.htm

 

He also discusses replacing the stock single horn with 2 units, at the same location as the single horn.

 

Can't help regarding the front battery not being connected - Sounds like you need to search around and find that positive cable. It should be there (famous last words) unless someone really hacked the de-installation of the police equipment (or if they pulled it due to some problems they may have been having with current drain, or worse like shorting). Mine arrived with both batteries hooked up (although the aux battery had essentially gone bad).

 

Good luck,

Tom

[RTP Rider]

Is this an ex-CHP bike?

 

If so, see the attached PDF. It may help explain/track down your problem. The CHP does a pretty massive re-wiring to accomodate LEO appliances (siren, strobes/led's, radio, PA, etc.). All tend to be interworking in nature, making for an interesting challenge when backtracking to fix a problem.

 

NOTE: The attachment is actually a PDF but the system doesn't allow us to upload a PDF so I renamed it a .txt file. Rename it a .pdf (or Acrobat may just open it up without renaming).

534060-CHP_HornRelay_Rename_to_PDF.txt

[Tschamp]

The attachment didn't work for me. Can you email it?

 

Thanks

[TMH]

RTP Rider:

 

Interesting little diagram. Hopefully you are a wealth of info on RT-P's, because I only recently got mine and I'm still trying to figure out all of the "authorities" differences.

 

Anything else in your treasure trove?

 

Thanks!

Tom

[DavidEBSmith]

There is a treasure trove of information at the BMW Police Motors site. Hope you have broadband.

[Nevets]

My RTP had almost the opposite problem, so I doubt this is your problem. When I picked up my 2003RTP earlier this year, I noticed no problem with the horn. After a week or so, the wife and I were leaving the neighborhood, and the horn beeped momentarily. She asked if I did that, and assumed I had somehow brushed the horn switch. After another hundred yards or so, it happened again. This time I was sure I had not hit the switch. What the?!?! Another hundred yards or so, and the horn came on, and stayed on. How to spell embarrassing? Needless to say, my wife was starting to wonder about our new BMW acquisition. So were the neighbors who were watching us, out for a walk on the street. I rode us back through the neighborhood, horn blaring away. After I stopped blushing and regained my composure, I realized I’d just unplug the horn, at the horn, and take it back to the dealer for a fix. Well, when I took it in, they said that since the police never use the horn, the switch contacts were probably dirty, and proceeded to squirt some contact leaner into the switch. As an electrical engineer, I was a little doubtful about that being the cause. It fixed it, and I’ve never had a problem since. And the wife will ride with me once again.

[99RT-P]

When I took delivery of my RT-P, the horn wasn't working. It turned out to be a simple broken wire located at the horn itself. Fixed the wire, and it was good to go.

 

Mine came with both batteries installed, but the backup battery was totally dead. I removed the battery and associated hardware, taped and bundled the wires out of the way. No electrical issues have popped up so far.

[KER]

For the RT-Ps the second battery runs all the lights and siren system. When all the lights are removed there is no use for the second battery anymore. Thats why most of them will be disconnected.

 

The horn should be working, the way the siren and air horn systems are setup it should work once the air horn is removed. Atleast that is the way both of my police bikes are setup. That is something that the dealer should take care of.

[TMH]

There is a treasure trove of information at the BMW Police Motors site. Hope you have broadband.

Couldn't ask for more. Thanks for the link!

 

Tom

[Tschamp]

Found the wires were worn and shorting. Fixed wire and replaced OEM horn with Freeway BBlaster low tone. Works great. Also added driving lights to the siren mounts on the crash bars. Thanks for all the input!

[rahbert]

There is one additional thing that the second battery provides power for - the dashboard accessory plug. I

am in the process of hooking it to the primary accessory

plug..

[Woodie]

Rahbert makes an excellent point. Took me quite a while to figure that out.

 

See the link in my sig for other things.

[GearedForACure]

No help here, but I thought that I would mention, my RTP was brought back up to police spec by the first (err...second) owner. The horn button is actually intertwined to the siren and lets loose a scquelch you would expect to hear from a fire truck. Its actually pretty cool, and quite alarming. Im not sure if it is legal though.

 

My worry is that it is too alarming and may scare a driver into a delay that will cost me, but I guess there is one way to find out, ride it, and use it.

[Turbodog]

No help here, but I thought that I would mention, my RTP was brought back up to police spec by the first (err...second) owner. The horn button is actually intertwined to the siren and lets loose a scquelch you would expect to hear from a fire truck. Its actually pretty cool, and quite alarming. Im not sure if it is legal though.

 

My worry is that it is too alarming and may scare a driver into a delay that will cost me, but I guess there is one way to find out, ride it, and use it.

 

Air horns are generally legal I believe, but sirens are not. The horn on my 1100rt-p is so pathetic I'm replacing it with the siren speaker and air horn amp. I have one on my Harley Road King police model and it really wakes up straying drivers.

 

As far as the second battery is concerned, I did like others and just disconected it, taped up the wires and left them outside the box. I use the box as a glovebox now.

I've also seen where someone mounted a radio inside his. Might do that someday since my rt-p has speakers in the consol.