horn relay T3

Could some kind soul explain to me how the horn relay should be wired up?I have returned home after spending 5 months in Brazil and naturally wanted a ride on the Guzzi. Tyres pumped up; fresh petrol in and a check that everything worked. No horn! I, being jet lagged, fiddled about with the relay and thought a new one would solve the problem. So of to Halfrauds to get a new one and then got into a muddle with which wire went where. I know, don’t say it! The thing is that I had a new Japanese horn/lights/indicator switch fitted under warranty a year ago and am wondering if there could be a bad connection there. I notice that there is a pinkish wire from the horn button which ties up with the Yamaha one as described in F.A.Q. section. I’m not too good on the sparks thing, but think I need to get the relay correct first don’t I? There is power to the relay by the way. Help please.(Note to self-don’t play around with bikes when jet-lagged) Cheers, Nick Brown.

Read the last but one gambo back page. it says for lights but the principle is the same.

Thanks Ian, I am still wading through 5 months worth of mail so, when I find the Gambalunga, I’ll have a look.



Here you go look at the diag on the fiog lights the principal is the same I guess there are other “how To’s” on line

First try the ‘flash’ button on your bike, the horn is wired up to the ‘flash’ button relay and so when you press the ‘flash’ button you should hear a Click from this relay, if so the relay is ok, if no ‘click’ then try replacing the relay try any old type car spares shop, not Halfords, take the old relay with you, the wiring on the three pin relay should be ‘87’ Green wire, from headlight bulb 85’ grey from lefthand handlebar switch the pin marked 30/51 should have three wires going to it via linked piggy backed spade connectors, one with a blue wire and a brown wire piggy backed together, and an other piggy backed spade connector with a brown wire .the blue is from the front brakelight switchone brown comes from the horn the other brown goes from the relay to the fuse box. have you tried a different 12 volt horn, any two pinned one will do.

northwest2012-05-02 21:48:31

You can also re-tune a horn if it plays up. Check to see if you are getting voltage to it first, If it is, then look for a small bolt possibly with a lock nut on it and turn it in or out slowly whilst keep pressing the horn button, just a little bit at a time and it might need wound in or out, it eventually should start to make a noise.

sometimes the horn will not work without the engine running if the battery is low, it does take alot of power… horns can also get waterlogged on a bike especially during a torrential drought

Thanks GuzziBear, I have looked at the ‘How to’ link and I am becoming less confused as to the function of the horn push button. The original relay had terminal 30 piggy-backed onto one of the others, so I think there is a clue there. When it stops p-----g down, I will drag the bike out of the shed and have another go now that I am back on UK time. NorthWest, my switch is a replacement Japanese one and there is no flasher, just lights on/off lo/hi beam, indicators and horn button. I have a spare battery so I can check that the horn itself is OK using that, I suppose. I did go to Halfrauds and get a 30a 4 pin relay, which as far as I can see, is a direct replacement for what was on there. Should I get a different one then; is there a problem with the stuff from Halfrauds? Anyway, thank you all for your response; I will let you know how I get on-or not-later.By the way, I have been in Brazil for 5 months and did not see one Guzzi!!! Mr. Honda seems to have it sewn up over there; they all ride the small singles and are completely mental!! Cheers from Nick Brown.

Halfrauds can be expensive compared to car accessory shops.
But not ridiculously so. And where appropriate cheaper than Guzzi.
Remember all that crap is made in the same Chinese factory, it just depends on the label.
Of course they are mental in brazil, where do you think the radio active nuts come from.

I’ve given the horn a quick try on a spare battery and it is fine. However, I did replace the original unit with the one from my Commando, which is a loud one from Norvil, though a single unit. Could that be a problem, perhaps I should go back to the original?

A12 volt horn is a 12 volt horn.
Make sure your -ve (earth) conection is ok.
Short a lead from bty +ve to horn +ve to show.
If this sounds the horn check relay is clicking.
If ok check fuse.
If all ok check connections then check relay by substitution (as you have already bought one).

This may sound nuts BUT some bikes the horn button puts +ve to the horn others a -ve, the Yam is opposite to the Guzzi, I guess if it is wired as it was then I would look for a corroded or broken wire

Halfords are ok for when you need something on a Sunday afternoon when all other car spares shops are closed, the problem is many of their staff cannot work out that some car bits also fit motor cycles, ie the old 1970’s Guzzis used points, condensers, ht leads, etc from cars, but the Halfords staff appear to be brainwashed into useing their parts book as a 100% bible, and for some of them the fact that ie a oil light switch for a Italian car can also fit a Italian motorcycle is something not in their bible so therefor “we dont stock motorcycle spares” is the same old reply I have heard from their stafff from their stores as far apart as Southampton and Blackburn, they do stock some m/cycle spares but just cannot handle that fact, I gave up on them years ago.according to my 1979 850T3 's hand book there are just two relays on the bike, one the four pin one under the right hand side panel, this is the starter relay, and the three pin, headlight/horn/flashing light relay, under the tank on the top fame rail, if your h/light/horn relay has four pins I presume this is due to the japanese switchgear,

On the V1000 these are in r/h side panel or under the seat. I have wondered about fitting a relay block under there now I have the space thanks to a smaller battery, as I have added

Headlamp relays and separated flasher and horn relay, added a relay for the spotlights so with the start relay that is a healthy 6, the relay block makes sense as I could populate it with Pyro Dan’s relays and have a spare lots easier to replace the errant start relay or a failed flasher relay as these have failed in the past.

When on occasion I have popped into a car parts place I always quote Fiat as the car… the fuel filter on the V11 also fits the Fiat Cinquecento, the ign key on the V1000 (T3 s etc) is a Zadi/Fiat blank any Timpsons have those. The oil pressure switch is also found on Fiat.

A wee bit of research on the good old web often turns up alternative parts. Have to say it is a hell of alot easier than finding alternative Japanese bike parts.guzzibear2012-05-04 11:55:44

[quote=“guzzibear”]This may sound nuts BUT some bikes the horn button puts +ve to the horn others a -ve, the Yam is opposite to the Guzzi, I guess if it is wired as it was then I would look for a corroded or broken wire[/quote] I assume my switch could be Yamaha (all I know is that the dealer replaced the old one with a Japanese switch). Anyway, I looked at the ‘how to’ site and after trying to get my head round why one should bridge the live to the relay from 30 to 85-which is what must have been done before- I went for it, and with the horn button wire to 86 and the output to 87; b----r me sideways, it works!! I hope this makes sense to you electrickery experts, because I still am a bit confused. Anyway, thanks again for your help: joining this club was a good move. There was a dodgy connection in the horn button wire and I have run a separate earth from the horn to the frame as well. Cheers from Nick Brown.

Yet another Reeeeesult…if you look in the Non oem list I have put a yamaha-Guzzi switchgear wiring list a few people have used it to rewire switchgear, it is a good move on older bikes …newer ones already have the same switchgear ( different coloured switch buttons is all) as Honda Firestorm and other new bikes