Horn not working - 2020 NC750S

[widu13 9]

I'll admit, only preliminary investigations so far but my horn not working. Before I start doing diagnostics, does anyone know what might be causing the horn not to work. It was feeble in use and then sort of faded out when used and hasn't worked since.

1. Fuses checked and all working
2. No other lights/electrical items out.
3. Good contacts with no corrosion at the horn spade connectors.
4. Horn tested off of the bike with a 12v source and works as it should.

 

I don't think these run off of a relay, so any ideas for a shortcut to the cause would be gratefully received.

[steelhorseuk 1,691]

Is it the OEM horn ? They are crap!

 

Replace it with something decent! I bought a good one (loud) from Halfords many moons ago which does the bizz.

 

Low/High Note Twin Snail Horn Pack | Halfords UK

Edited May 16, 2023 by steelhorseuk

[listener 11,213]

27 minutes ago, widu13 said:

I don't think these run off of a relay, so any ideas for a shortcut to the cause would be gratefully received.

 

No, they don't run off a relay.

 

Since the horn works (point 4) it appears to be an issue further up the line.

 

It could be dirt in the horn switch - spray some contact cleaner or WD30 into the switch block.

 

If you have a multimeter stick it across the terminals that feed the horn and check for 12V when you hit the horn switch.

If not, you can jury-rig a 12V <5A bulb and use that instead of the meter.

Edited May 16, 2023 by listener

[fred_jb 10,265]

These sometimes have an adjuster screw to tune them to max volume.  If yours has one you could tweaking that.

 

Edit:  probably won't make a difference if it works off the bike.

 

Edited May 16, 2023 by fred_jb

[widu13 9]

1 hour ago, listener said:

 

No, they don't run off a relay.

 

Since the horn works (point 4) it appears to be an issue further up the line.

 

It could be dirt in the horn switch - spray some contact cleaner or WD30 into the switch block.

 

If you have a multimeter stick it across the terminals that feed the horn and check for 12V when you hit the horn switch.

If not, you can jury-rig a 12V <5A bulb and use that instead of the meter.

 

Cheers I'm okay with the testing, just haven't got any spare time at home this week hence asking for the quick fixes. A squirt is a good idea that I had completely overlooked...I've got some contact cleaner knocking about somewhere. 

[widu13 9]

2 hours ago, steelhorseuk said:

Is it the OEM horn ? They are crap!

 

Replace it with something decent! I bought a good one (loud) from Halfords many moons ago which does the bizz.

 

Low/High Note Twin Snail Horn Pack | Halfords UK

 

Got a low note Fiamm to chuck on once power is sorted.

[fred_jb 10,265]

When you get around to testing, the presence of 12V across the two wires feeding the horn does not necessarily mean it is OK.  If there is a high resistance in the circuit, for example from a corroded connection somewhere, then it could measure 12V when open circuit, but be unable to flow enough current to properly operate the horn.

 

One thing you could check is to see if the earth connection for the horn goes back to a connection to the chassis somewhere and see if that is secure and not corroded.

 

[Andy m 23,586]

18 minutes ago, fred_jb said:

When you get around to testing, the presence of 12V across the two wires feeding the horn does not necessarily mean it is OK.  If there is a high resistance in the circuit, for example from a corroded connection somewhere, then it could measure 12V when open circuit, but be unable to flow enough current to properly operate the horn.

 

This is where a test lamp or headlight "bulb" beats a multi-meter.

 

Lamp across the two wires, then wire on the lamp grounded via It's own wire direct to the frame, then jumper from battery positive through the lamp and using the earth in the loom.

 

Assuming you find one missing, follow the wires up to the first connector. There is always one to allow the switch gear to be replaced.

 

Andy

[widu13 9]

1 hour ago, Andy m said:

This is where a test lamp or headlight "bulb" beats a multi-meter.

 

Lamp across the two wires, then wire on the lamp grounded via It's own wire direct to the frame, then jumper from battery positive through the lamp and using the earth in the loom.

 

Assuming you find one missing, follow the wires up to the first connector. There is always one to allow the switch gear to be replaced.

 

Andy

 Cheers Andy & Fred. Just home and 14.5v at the connectors, so more in depth work required. I'd be surprised if it's corrosion as A. It's not even 3 yrs old and B. I'm assuming it's a common earth- nothing else is affected.

[fred_jb 10,265]

Was the 14.5V measured with the engine running?  If not it seems rather high as I would expect more like 12.5V.

 

When you tried it off the bike did you hold it in the same orientation as it is on the bike? If not I'm wondering if there is a dodgy connection inside the horn which is better in some orientations than others, or even some mechanical misalignment.

 

 

Edited May 16, 2023 by fred_jb

[widu13 9]

Ok, problem rectified but wasn't resolved. It was switch related. Fred- yes 14.5v with engine running. No matter was I tried at the terminals I could not get a test lamp lit. I didn't know what the Amps were supposed to be so an Amperage test wasn't going to assist me. I opened up the switch gear and the horn had two soldered connections- black and red but I could see that it joined into a loom. A good squirt of contact cleaner and I could hear the click of the horn attempting to sound. It felt as though there was a very slight give in the travel of the horn button and it travelled further in making contact briefly and sounding the horn. More cleaner followed by some silicone grease and the horn is now operating, but in reality its a bodge rather than a fix. Then I made up some small extensions and fitted the Fiamm horn. So working for now. I'm not convinced that the contacts were obstructed...they're certainly not corroded, I suspect that the cleaner acted as a lubricant allowing further travel to make the switch contact.

 

Thanks everyone for the input.