Faulty Horn

[scotty]

Need some help again.

I'm just getting the bike ready for an MOT and it has'nt been used for a couple of months. Just noticed that the horn is not working. I have checked the fuse which is under the tank and that's ok. I have also disconnected the horn and tested it directly to a battery and it works fine. I'm therefore stuck with the problem being from the switch to the horn itself. Before taking the switch apart does anyone have any ideas as to where the fault might lie. I have also noticed that the hazard warning light on the left hand switch is always lit up even when the hazard lights are off or on. This struck me as a bit unusual as I would imagine that the red light on the button should only light up when the button is pressed on. If this is faulty then there could also be a problem with the horn switch. Also is it a fairly straight forward job to take the left hand switch unit appart or are there going to be loads of small spring's and clips flying all over the place. Apparently BMW don't stock switch parts but only the whole unit. I'm not prepared to buy a new unit so will have to try and fix the existing one. Any tips/help on this would be appreciated before I pull the thing apart.

Thanks again

[Paul]

That old chestnut. I believe the answer to your question probably lies in this thread. Wires rubbed through against the front left hand relay box, I would bet.



Cheers,

Paul

[scotty]

Thanks Paul

You've obviously sorted this one out before. I was poking about that area last night and could'nt see anything amiss so I'll have another look tonight. Can you shed any light on the hazard button which is on all the time. Is this right or should the red button only light when the hazard lights are on ?

[madman]

Both of our bikes have the illuminated hazard button.

[sproggy]

Can you shed any light on the hazard button which is on all the time.

Same as on most modern cars - the hazard switch is illuminated whenever the ignition is on. This is so you can find it when you break down in the dark Assuming, of course, that your breakdown isn't caused by a total electrical failure

Anyway, it should be on all the time - nothing to worry about. I think it flashes when the hazard lights are activated, but I can't remember.

[Jason M]

Need some help again.

I'm just getting the bike ready for an MOT and it has'nt been used for a couple of months. Just noticed that the horn is not working. I have checked the fuse which is under the tank and that's ok. I have also disconnected the horn and tested it directly to a battery and it works fine.
Thanks again

I had exactly the same problem for my MOT this year. It might not be the switch - I quickly plugged in a spare left hand switchgear into the loom and that wasn't it either. I think the switch works a relay - you might be able to hear it clicking. The wiring for it is very protracted. I think the switch goes to a relay in the right hand relay box - you'd need to take the faring off to see it. I think the power and earth comes round the right side of the bike to the relay and that seemed to be where my problem was somewhere. I ended up putting another circuit in switched through a new relay as you cannot get at the little fecking connectors to the BMW relays without a tiny magic wand (read special little tool ) and I had a little 'wire rage' accident and broke one While I was at it I got a LOUD horn from Nippy Normans - excellent!

Jason

PS - thisflippin hot weather makes me flippin short tempered. Today I 'Zidaned' my keyboard in a fit of pique and had to walk around with QWERTY embedded in my forehead

[winny2]

If you ride the same as I do and only use the horn once a year at MOT time, then you may find it's just a rust build-up in the horn itself. A tap from a long proddy thing or rubber hammer might cure it.

Surprised you didn't mention it Jason.

[scotty]

Jason

I think your horn problems sound the same as on my bike. I checked for frayed wires last night and this is definitely not the issue. All wires in perfect order. I even cut a couple of cable tidy's to check the hidden part of the wires and everthing is ok. Like yourself when I press the horn I can hear a clicking sound coming from the front of the bike and it definitely sounds like some kind of relay switch. I could'nt figure out exactly where is was coming from though and it was really annoying. The cable from the horn joins a larger group of cables at the left side of the bike which then enters the large plastic junction box at the left side of the bike. Where is the relay switch that could be faulty ? Is this situated in the right hand large black plastic junction box ?

The problem with your bike sounds the same as on mine though. The horn switch seems fine ands that is why I hav'nt pulled it appart. Christ what a commotion kust to fix a horn. Can't get it through the MOT until I do this though.

[scotty]

Jason

Just thought of somtheing. If the problem can be traced to the right hand junction box. What unit do you think need replacing ? I've only looked inside the left junction box and there are several unit/boxes. I would assume that inside the right junction box would be the same. What unit did you replace ? Also, did you need to do any soldering of wires or was it a case of simply plugging in a new unit ?

Thanks

[boxerpan]

Jason

Just thought of somtheing. If the problem can be traced to the right hand junction box. What unit do you think need replacing ? I've only looked inside the left junction box and there are several unit/boxes. I would assume that inside the right junction box would be the same. What unit did you replace ? Also, did you need to do any soldering of wires or was it a case of simply plugging in a new unit ?

Thanks

In most cases it is a wearing away of the insulation on the wires as they go into the plastic boxes. Soldering new wire sections in and re-sheathing the insulation should sort it out.

[bigblackfalco]

Had probs with my horn once( they all say that ).
It was the horn itself.The only true test is to connect it directly to a battery.
It takes quite a bit of ooommmppphh to work a horn properly.Sometimes a good hefty pulse of voltage sorts em out.
Also check the earth on the mountings and the earth to the horn and relay;whilst you may have healthy voltage at all points, you might have a poor earth somewhere which is causing a bad circuit.
Usually if you can hear clicking from the relay it means the relay is OK.Also you can sometimes hear clicking noises from the horn itself ( like it's trying to vibrate but can't). If you can locate the adjuster screw on the unit( I think they are waxed off on these ones?) then give it a few turns in either direction.
I can strongly recommend the twin horns used on the NTV.....excellent for waking the cagers and peds u, and you can probably pick them up from a breaker for a few coppers
Bailey.

[black99S]

Need some help again.

I'm just getting the bike ready for an MOT and it has'nt been used for a couple of months. Just noticed that the horn is not working. I have checked the fuse which is under the tank and that's ok. I have also disconnected the horn and tested it directly to a battery and it works fine. .... Any tips/help on this would be appreciated before I pull the thing apart. Thanks again

Did you try the horn with the engine running?
Not used in a couple of months = low battery and all you will get is a clicking from the horn when not running as the voltage is low and pulled down lower with your headlight etc. drawing power.
/rd

[Jason M]

Jason

Just thought of somtheing. If the problem can be traced to the right hand junction box. What unit do you think need replacing ? I've only looked inside the left junction box and there are several unit/boxes. I would assume that inside the right junction box would be the same. What unit did you replace ? Also, did you need to do any soldering of wires or was it a case of simply plugging in a new unit ?

Thanks

The horn relay I think is the one closest to the front of the bike in the right hand junction box. You can take the bottom of those boxes off and check the feed to the relay - I think the switched circuit wasn't earthing on mine so the relay was working correctly from the switch, but the horn circuit it was connecting was dead. As I said, I could not remove the connectors from the relay box (read I fu*ked one up 'trying' with a variety of screwdrivers etc but there is magic involved and I didn't have the necessary wand. I think Boxerdog has a tiny tool - sorry Bob! - that you can get to remove the connectors and therefore rewire the current relay) so I think I ran another fused (inline) circuit from the battery through the horn on its way over to that junction box and just put another relay loose in the junction box switched by the horn circuit (just cut the horn wires to the relay and put some new connectors on to the new loose relay)

I just remember it was a right royal pain in the arse - if you need a diagram of what I think I did then let me know. It's got to be straight forward electrics if I can do it though

Jason

[scotty]

Jason

I think your diagnosis may well be the right one. I checked the relay last night by swapping the relay's round as there are two identical ones in the right junction box. No cure though so the problem sounds like the wires feeding into the relay itself. The relay was clicking away quite happily so the switch on the handlebar seems ok. At least that's something as I did'nt fancy having to replace that as they are costly. I did partially unclip the bottom of the junction box last night just to have a quick look but did'nt go any further. There is quite a few wires bundled in there. Getting the bottom of the junction box off looks a bit of a pain as one has to unbolt the two allen bolts holding the box. The back one is easy but I'll have to cut through a few cable tidy's and re-route the large group of wires coming out of the front of the box to get to the front allen bolt. Once that is done I should have enough room to get at the wires inside. However, any assistance you might be able to give in the shape of a diagram would be great. You were also saying that there is a special tool that can be purchased to disconnect the wires from the unit. If this is'nt too costly I might as well buy one. Any idea as to what this costs or the part nos ? What should I be looking for when I have access to the necessary wires ie bad connection, corrosion, broken wire ?

[scotty]

Just got in contact with Darren at Motorworks who owns a R1100s. He was saying that the most common problem with the horns on this model is the tiny connection pins that BMW use to connect the horn to the wiring loom. It's worth checking with a voltmeter or bulb to see that power is getting down to the horn as the connector pins may not be making contact with the wires in the connector. I noticed these tiny pins when I checked the horn directly to the battery and considered them totally naff so the problem could well rest here. Unfortunately my voltmeter is somewhere else at the moment so I'll have to rig up a bulb to test this. If this is the problem Darren was saying that one could put a tiny kink in the horn pins which should make a proper connection to get the thing working. Hopefully this will be the problem so Jason.... hold off with the relay wiring diagram until I check this one. Fingers crossed this may be it as I don't really fancy poking around with the wiring under the relay. Darren was saying that a lot of 1100s owners just scrap the horn and upgrade using one with spade connections. Sounds a good long-term solution if this is the problem.