 | Home > In Car Electronics > wiring twin horns, not air |
 
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| donmacn Member Since: 07 Nov 2017 Location: Nth Scotland Posts: 1829  |
I have to say I followed Clayton’s lead, fitted those PIAA horns to the factory wiring and am pretty happy.
Jeffers - I take it you’re switching the relay (turning the horns on) using the feed from the original switch? Or have you done something else to the switch side wiring?? If you’ve taken the original power wire, and used that to power the relay, then I’d be as stumped as you without some serious study of the wiring diagrams. So the switching side would be ‘original horn power to relay’ and then earthed directly on the other side; with the power side from battery to horn and earth? I think you can take it the battery/power side is working, so the issue is why is there no power with the engine running (sorry - you know that… just thinking out loud!) Donald 1994 Defender 300Tdi 110 SW - owned since 2002 - 230k miles and going strong (The 'rolling restoration' or tinkering thread: http://www.defender2.net/forum/topic58538.html ) 2000 Range Rover P38 4.0L V8 in the past.. RR classic - fitted with 200Tdi 1984 RR classic - V8 with ZF auto box 1993 Discovery 300Tdi not to mention the minis and the Type 2 VW camper... |
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5th Nov 2021 6:45pm |
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| jeffersj Member Since: 23 Jan 2015 Location: Near Preston Posts: 431  
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Donald thanks for the response. Yes I am using the original switch on the stalk and the original horn wiring.
The units are earthed through the fixings and so one of the original horn wires remains unused ? (according to the wiring diagram supplied). Darren suggested that the relay would still need to be earthed but not sure how as all 4 pins are being used. It is just weird how with engine running there is no horn, I do not have any diagnostic tools unfortunately. When I thought I had sorted the probelm it was all done without engine running so it was only on the road when I realised. I might try using the unconnected original horn wire and taking it to an earth and see what transpires. Stil it keeps me busy! Jeff Ex 1968 Series 2A Ex 90 TD5 Ex D3 Ex D4 |
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6th Nov 2021 10:11am |
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| donmacn Member Since: 07 Nov 2017 Location: Nth Scotland Posts: 1829 |
Hi Jeff,
Have you pictures of the setup? I remember the first time I played with relays I was really surprised how straightforward they were - though I know some are more complex than others. Are you using a common four pin relay? I think the original wire supplying power to the horn is black and purple, or purple and black. Two colours anyway. This is the one, coming from the stalk, that you’re using to activate the relay? If so, then the pin opposite that needs to be earthed in order to activate the relay and let power flow through the new cable from battery to new horns. If anything comes across as too patronising please excuse me! There will be a little picture on it somewhere showing how the pins work. Current flowing across two pins completes the circuit for the other two pins. You’ll want the new cable - battery to horn, to be the circuit that’s normally broken. Then the other two pins are your power supply from the horn, and then to earth. It’s simple enough, but complicated to describe! Happy to exchange phone number by PM if you think that would help? Donald 1994 Defender 300Tdi 110 SW - owned since 2002 - 230k miles and going strong (The 'rolling restoration' or tinkering thread: http://www.defender2.net/forum/topic58538.html ) 2000 Range Rover P38 4.0L V8 in the past.. RR classic - fitted with 200Tdi 1984 RR classic - V8 with ZF auto box 1993 Discovery 300Tdi not to mention the minis and the Type 2 VW camper... |
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6th Nov 2021 11:38am |
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| jeffersj Member Since: 23 Jan 2015 Location: Near Preston Posts: 431
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Donald I have added a poor photo of the wiring diagram included with the horns (on the cardboard box)!
The photo also shows the horns with 2 pins but there is only 1. You will see that relay pins 30 and 86 take the live feed from the battery, 85 has the original horn wire and 87 takes the feed to the horns which are earthed through the fittings. The diagram suggests that the other horn wire is taken to earth which I have not done as I queried this with the supplier who confirmed that it was unconnected? Whilst 87 is the "negative" feed and to earth through the horns, hard to see if I should add an earth connection to this pin? Think I will have to try connecting the unused horn wire to an earth and see what happens.  Click image to enlarge Thanks so far Jeff Ex 1968 Series 2A Ex 90 TD5 Ex D3 Ex D4 |
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6th Nov 2021 3:28pm |
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| donmacn Member Since: 07 Nov 2017 Location: Nth Scotland Posts: 1829 |
Hi Jeff,
I have to nip out now for a couple of hours, but I can do a similar drawing suggesting an alternative layout. One of the issues, based on a quick look, is that the switch doesn't earth at the steering wheel end, but down by the horns. If you've not fixed it by the time I'm back I'll fire something up here. Donald 1994 Defender 300Tdi 110 SW - owned since 2002 - 230k miles and going strong (The 'rolling restoration' or tinkering thread: http://www.defender2.net/forum/topic58538.html ) 2000 Range Rover P38 4.0L V8 in the past.. RR classic - fitted with 200Tdi 1984 RR classic - V8 with ZF auto box 1993 Discovery 300Tdi not to mention the minis and the Type 2 VW camper... |
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6th Nov 2021 3:37pm |
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| jeffersj Member Since: 23 Jan 2015 Location: Near Preston Posts: 431
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Thanks Donald! Most of the wiring daigrams on the web suggest straight forward connections in parallel without a relay but the horns have 2 pins on those diagrams.
A bit wild out there now so given up for today! Jeff Ex 1968 Series 2A Ex 90 TD5 Ex D3 Ex D4 |
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6th Nov 2021 3:46pm |
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| donmacn Member Since: 07 Nov 2017 Location: Nth Scotland Posts: 1829 |
Ok, a bit rough and ready, but here's a diagram representing the way I would do it, and the way I imagine it would work. I've kept it with the terminals in the order of the suppliers diagram.
Click image to enlarge The original power to the horn (purple/black) goes to terminal 85. Your new wiring from the battery and fuse comes to 30; then continues on to the horns from 87. 86 just needs a little length to earth somewhere. You could use the black wire from the original horn installation, or depending on how you've mounted the relay, just a short length of black wire with a ring terminal at one end; a female spade on the other. Connect the spade to terminal 86 and then the ring terminal to the screw you've used to mount the relay. Sometimes a wee scrape of the paint there to be sure of a contact would work. If you reckon the circuit was working previously, there is no reason not to use the original wiring. Then you just do the 'piggyback'/loop to take power from #1 horn to #2 horn. They will be earthed via the fixings. Hopefully you've got all your wires made up with the terminals, and it would just be a 2 or 3 minute job to make sure they were plugged into the right places. If this set up doesn't work, then you could do more 'diagnostics' but try this first. When I first started tinkering with electrics, I didn't have a multimeter - and I'm still not sure about most of what it does! But I did buy one of those wee 'illuminating probes' - like this:
(Edit - this one is £7 from Amazon, but you could probably find one in any Halfords or car accessory shop) In your scenario, if you'd had one of these, you could have clipped the crocodile clip onto any good bit of metal (engine block, bare bodywork) as your earth, and then put the pin into the power supply to the horn. Push the button, and if it lights up, you've a good circuit. It's dead simple, and can help track faults. I still keep one in my 'mobile' tool box. It's pretty rubbish up here today as well. I've abandoned the garage and spent the day inside setting up a new PC! Cheers Donald 1994 Defender 300Tdi 110 SW - owned since 2002 - 230k miles and going strong (The 'rolling restoration' or tinkering thread: http://www.defender2.net/forum/topic58538.html ) 2000 Range Rover P38 4.0L V8 in the past.. RR classic - fitted with 200Tdi 1984 RR classic - V8 with ZF auto box 1993 Discovery 300Tdi not to mention the minis and the Type 2 VW camper... |
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6th Nov 2021 5:24pm |
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| jeffersj Member Since: 23 Jan 2015 Location: Near Preston Posts: 431
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Thanks Donald, I can give it a try and the probe sounds like a good idea. Jeff
Ex 1968 Series 2A Ex 90 TD5 Ex D3 Ex D4 |
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7th Nov 2021 10:31am |
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| jeffersj Member Since: 23 Jan 2015 Location: Near Preston Posts: 431
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UPDATE - another few hours of my life that I will never get back!
Donald tried your wiring set up and had no horns at all so I rewired everything according to the supplier's diagram and back to the conundrum, horns work without ignition, horns work with ignition on but as soon as the engine is running no horns? Headlamp flasher not working either but dipped beam, main beam etc all working so I am starting to go back to thinking that during the messing about something (me) has shorted some part of the stalk wiring out. I have a new stalk so will give that a try and if this is not the solution then I may go back to one pathetic horn or buy twin horns with 2 pin fitting and connect them in parallel! 
Dorset Smith this is a one for you I think. Jeff Ex 1968 Series 2A Ex 90 TD5 Ex D3 Ex D4 |
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7th Nov 2021 4:01pm |
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| donmacn Member Since: 07 Nov 2017 Location: Nth Scotland Posts: 1829 |
Hi Jeff,
Damn! If all the wiring's in good nick, with no shorts or blown fuses, then the set up I drew should work. Do you have a 'lovely assistant'? If so, then I would recommend getting one of those illuminating tester probes asap. That way you could put the probe between the original power supply (the bit you're connecting to pin 85 on the relay) and an earth > have your assistant press the horn stalk > the probe should light up while the switch is being pressed. If not, then that's one of your problems - maybe a short leading to a burst fuse as you've suggested. You could also double-check your new wiring with it, by connecting it across the two ends of your new battery to horn wiring. (the spades that go in at 30 and 87) Again, it should light up, if not there could be an issue with the connections at the battery end, or the fuse. That's less likely, but not impossible. I think some basic diagnostics of the circuits is needed just to be sure you have power in the wiring where you need it. I would do that before I went to the extent of changing the stalk - that's not so straightforward in my experience. I can't remember if the same fuse does the headlamp flashing and horn?? If so, then definitely check that. I think the diagram from the horn supplier doesn't really work, as it shows the earth at the switch end, whereas I believe the earth happens at the horn end. The reason you're getting the 'symptoms' you are will be to do with some weird routing of power and earth. Donald 1994 Defender 300Tdi 110 SW - owned since 2002 - 230k miles and going strong (The 'rolling restoration' or tinkering thread: http://www.defender2.net/forum/topic58538.html ) 2000 Range Rover P38 4.0L V8 in the past.. RR classic - fitted with 200Tdi 1984 RR classic - V8 with ZF auto box 1993 Discovery 300Tdi not to mention the minis and the Type 2 VW camper... |
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7th Nov 2021 4:36pm |
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| jeffersj Member Since: 23 Jan 2015 Location: Near Preston Posts: 431
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Thanks again, I will not be beaten by a machine so will perservere. Jeff
Ex 1968 Series 2A Ex 90 TD5 Ex D3 Ex D4 |
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7th Nov 2021 4:52pm |
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| jeffersj Member Since: 23 Jan 2015 Location: Near Preston Posts: 431
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Just been studying the wiring diagram in the Haynes Manual (most complicated) and just wondered if i have over complicated things by taking a direct fused feed form the battery rather than just using the original horn wires i.e taking the live feed horn wire to pins 30 and 86 the negative feed to pin 85 and the lead to the horns from as per the suppliers diagram?
Would this direct feed be affecting the horns when the engine is running by bypassing Fuse FL1? Just a weird thought. Jeff Ex 1968 Series 2A Ex 90 TD5 Ex D3 Ex D4 |
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7th Nov 2021 6:17pm |
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| jeffersj Member Since: 23 Jan 2015 Location: Near Preston Posts: 431
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FINALE Beaten by machine again. I checked fuse and it had blown as Donald suggested but because I was taken power direct from the battery the horns worked as before (except when the engine was running).
With a new fuse i tried both the supplier's wiring set up and Donald's but no change so thinking stalk might be at fault decided to refit old horn using the original wires without the direct feed from the battery and that worked fine, but much louder and clearer! Probably becuase I had replaced most of the connections. It is possible that the relay was frazzled also but not bothering for now. Stalk fine and horn working fine including headlight flasher so have given in! The only benefit being that I now have a loud single horn and a spare direct battery feed in the engine compartment should I need it in future. Thanks for all the help until the next time! Jeff Ex 1968 Series 2A Ex 90 TD5 Ex D3 Ex D4 |
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8th Nov 2021 5:58pm |
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| donmacn Member Since: 07 Nov 2017 Location: Nth Scotland Posts: 1829 |
If it works…… walk away and have a drink to celebrate!
Glad to hear you have got something sorted. Forgot to ask earlier what the vehicle’s history is, and whether it’s possible that there was something non-standard going. But now that you’ve got it going I’ll keep that to myself! Donald 1994 Defender 300Tdi 110 SW - owned since 2002 - 230k miles and going strong (The 'rolling restoration' or tinkering thread: http://www.defender2.net/forum/topic58538.html ) 2000 Range Rover P38 4.0L V8 in the past.. RR classic - fitted with 200Tdi 1984 RR classic - V8 with ZF auto box 1993 Discovery 300Tdi not to mention the minis and the Type 2 VW camper... |
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8th Nov 2021 9:25pm |
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