[Tigers] Horn Wiring

Theo Smit tsmit at shaw.ca
Mon Sep 25 20:15:05 MDT 2023 

Attached is a wiring diagram image suitable for wiring in a typical Bosch style cube relay (with included fuse), such as is sold through this Amazon listing:
https://www.amazon.com/APIELE-Relay-Normally-Harness-Socket/dp/B0B1TF3DTV/ref=sr_1_43?crid=337OR55GZFBVN&keywords=cube%2Brelay%2Bwith%2Bfuse&qid=1695689958&sprefix=cube%2Brelay%2Bwith%2Bfuse%2Caps%2C151&sr=8-43&th=1
APIELE 4 Pin Relay 12V 40A Relay with 30A Fuse DC SPST Fused Relay Normally Open 1NO with 14 AWG Harness Socket for Car Truck Motor
amazon.com

This relay includes a connecting socket with color coded wires. I’ve indicated the color as well as the Bosch standard reference numbers on the diagram.

The fuse is there to protect the horn wiring. The relay is typically beefy enough to pass 30 amps, but the OEM purple wires are going to melt before the OEM 35 amp fuse blows if you ever had a dead short in the horn circuit. Since the horns themselves should not draw more than about 6 amps, it should be fine to put a 15 amp fuse in the relay’s fuse holder. That will ensure that if you have a short (at least downstream of the fuse…) it will blow the fuse before it destroys your wiring.

If you run the circuit as shown, the ‘hot’ side of the relay output (red wire) can drive either the horns you currently have, with a built-in ground, or they could drive the OEM or the Hella horns if you then wire the other terminal of each horn to ground as shown in the diagram.

Let me know if you have any questions.



> On Sep 25, 2023, at 4:28 PM, Theo Smit <tsmit at shaw.ca> wrote:
> 
> Based on the review info on Summit, the Hella horns have the same wiring as the OEM Clear Hooters so you should be good to go. Another source I found indicated the power consumption is 72W so that should be 6A at 12V, the same as OEM also. You would still be best off with running these through a relay.
> 
> https://www.hella.com/MicroSite/horns/en/index.html
> 
> On Hella's site you can hear what they sound like.
> 
> Cheers,
> Theo
> From: "Bob Wanty" <bobwanty at gmail.com>
> To: "Joe Brown" <jbbrown1980 at gmail.com>
> Cc: "Gary" <garywinblad at comcast.net>, "Theo Smit" <tsmit at shaw.ca>, "tigers" <tigers at autox.team.net>
> Sent: Monday, September 25, 2023 3:33:19 PM
> Subject: Re: [Tigers] Horn Wiring
> 
> I found the original horns in a box but they did not work. I might give the Hellas a try
> 
> On Sep 25, 2023, at 4:48 PM, Joe Brown <jbbrown1980 at gmail.com> wrote:
> 
> I attempted to repair my original horns but the wiring inside was crumbling.  I saved them for a future project.  What I installed in my car was a pair of Hella dual trumpet horns.  You can see them at https://www.summitracing.com/parts/hla-007424801.  They come with a relay and they mount up in the original locations with the original wiring.  I didn't use the relay but I might go back and add it.  I tested them before I installed them and they were really loud but they didn't seem to be as loud after I installed them.  So I'm guessing that if I rewire them and use the relay I can get more current to them and have a louder sound.
> Have Fun,
> Joe Brown
> 
> On Mon, Sep 25, 2023 at 3:21 PM GARY WINBLAD <garywinblad at comcast.net <mailto:garywinblad at comcast.net>> wrote:
>> Most all aftermarket horns have only one terminal or have 2 terminals that are both 12V.
>> There was only one brand that Paul Reisentz found to use.. I wish I could remember.
>> I think it was SPAL (the fan guys) but googling I can't find them.
>>  
>> I remember because I dissected a defective original horn for him.  Unlike Theo, I couldn't
>> see any way to fix that one.
>>  
>> Bob, you will probably need to look for some original horns (that still work) or add a relay for the
>> fans you already have.
>> Gary W.
>>  
>>  
>> On 09/24/2023 8:08 PM PDT Bob Wanty <bobwanty at gmail.com <mailto:bobwanty at gmail.com>> wrote:
>>  
>>  
>>  
>> My horns have a single terminal so I will get two terminal horns. The relay idea sounds good.
>> Thanks for the help.
>> Bob
>> 
>> On Sep 24, 2023, at 9:45 PM, Theo Smit <tsmit at shaw.ca <mailto:tsmit at shaw.ca>> wrote: 
>> 
>> Hi Bob,
>>  
>> The wiring diagram here: http://tigersunited.com/resources/wsm/tt-images/MKIABIGwiring.jpg shows two solid purple wires to the horns feeding 12 volts, and two purple with black stripe wires that are the horn ring connections. There is no separate jumper wire from one horn to the other; if your car has that then it was added by a previous owner.
>> <Screenshot 2023-09-24 at 7.34.26 PM.png>
>>  
>> But, if the horns already start to sound when you connect just the hot side, then there is an internal short in at least one horn, which is not how it's intended to be. if you have an ohm-meter that can measure very low resistances then you can take measurements across the two horn terminals and from each terminal to the horn body (or the frame mount). That would help you isolate where the wiring problem is.
>> <Screenshot 2023-09-24 at 7.38.18 PM.png>
>> This is a sketch of the high-tone horn. The low-tone horn has an L cast into the bell. The two terminals connect (through the wire coil and the points) to each other, but there should be no connection to the horn body itself. The way you're describing the operation of your horns, connecting one of the terminals to hot causes the horn to go, even if the other wire is not connected (or, without pushing the horn ring on the steering wheel). 
>>  
>> Do both horns work the same way (i.e. they go off when only the hot is connected) or does only one horn do that? If one horn works properly (connect the purple wire to one terminal, connect the purple-with-black-stripe wire to the other) then that horn is fine and it's the other one that has an internal short. It can probably be fixed by opening the horn up and figuring out where the short is.
>>  
>> Theo
>>  
>> From: "Bob Wanty" <bobwanty at gmail.com <mailto:bobwanty at gmail.com>> 
>> To: "Theo Smit" <tsmit at shaw.ca <mailto:tsmit at shaw.ca>> 
>> Cc: "Tom Witt" <atwittsend at verizon.net <mailto:atwittsend at verizon.net>>, "tigers" <tigers at autox.team.net <mailto:tigers at autox.team.net>> 
>> Sent: Sunday, September 24, 2023 6:41:37 PM 
>> Subject: Re: [Tigers] Horn Wiring
>>  
>> Thanks for the responses.
>> Everything is wired to the horns, they look original. There are 2 purple wires to each horn, one is hot from the fuse box the other wire goes to ground when the horn ring is pressed. When I plug the hot wire to the  horn it works fine, even honks. So the horns must not be original since they are grounded to the frame.  I still have 4 purple wires when I only have connections for two and the wiring diagram only shows two wires, one to each horn.
>> So should I isolate the horn frame ground, plug the hot wire to the horn, use the existing jumper between the horns and connect the horn ring wire to the other horn?
>> 
>> On Sun, Sep 24, 2023 at 1:50 PM Theo Smit <tsmit at shaw.ca <mailto:tsmit at shaw.ca>> wrote:
>>  
>> Correct except that Rootes (or Lucas) would never use a relay where they could instead pass all the current through a finicky sliding contact. 
>>  
>> Bob, the horns, when properly adjusted, draw about three amps each. It would be a good idea to wire in a cube type relay so that the ring contact does not have to pass that much current. 
>> If you like I can draw up a wiring diagram for that. 
>>  
>> Theo 
>> On Sep 23, 2023, at 10:52 PM, Tom Witt via Tigers <tigers at autox.team.net <mailto:tigers at autox.team.net>> wrote: 
>> 
>> I believe most horns have a relay and the 12v+ is already at said relay. When the horn ring makes contact it GROUNDS the relay (completing the circuit) and the relay contact points connect. That passes through the 12V+ to the horns. So, typically the horn ring simply grounds the relay to activate it. Sorry too late for me to check the manual for Tiger specifics but MOST cars function that way.
>> 
>>  Think of yourself standing at a light switch in the house. When someone presses you on the shoulder (connecting to ground) you and the switch act like the relay moving the switch to the on position. This then send power to the light (horn). When the person pressing on your shoulder releases you turn the switch off. Hope that helps.
>> 
>>  
>> On 9/23/2023 5:59 PM, Robert Wanty wrote:
>> I am working on wiring the horns for the first time since my 15 year restore. I am working with the original wiring harness and horns. Starting at the horns there is one on  each side with a jumper wire between the two horns, there are 2 purple wires leading to each horn, one wire on each side is hot  and wired to the fuse box the second wire is not hot or grounded. I installed a new horn ring from SS and have one wire from the contact on the horn ring and a second wire for the circle contact off the signal switch, I think the wire for the circle contact should be hot  but I don't seem to have a connector for it in the harness under the dash and nothing for the wire to the horn ring.
>> It would seem to me that I should have a hot wire to the ring contact then a hot to the horns when the horn ring is pressed. but the wiring harness does not seem to follow that way of thinking. 
>> The wiring diagram is some help but as usual my limited knowledge on this will probably start a fire.
>> Any help would be appreciated, I would rather not rewire the circuits so hopefully I can restore the Lucas system.to <http://system.to/> its original splendor.
>>  
>>  
>> Bob 
>>  
>> 
>>   
>> 
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