This is the one I used "cause I already had it in my SparePartsBag in
my VDubaru

http://www.radioshack.com/product/index.jsp?productId=3020762

        Orig

_______ +12V ______ Horn ________ HornSwitch On SteeringWheel ________
Ground

        New WithRelay

_______ +12V _____ Relay 86 & 87 ___ 85 ___ HornSwitch On
SteeringWheel _____ Ground
                                        Relay 30 _____ Horn ______ Ground

        The +12V - 87-30 Circuit can be before or after the Horn & can be
30-87 if you desire

        The +12V - 86-85 Circuit (to HornSwitch On SteeringWheel) can be +12V
- 85-86 if you desire

                                                                                        ORR ~ DeanB
On 21 Aug , 2013, at 5:17 PM, mark drillock wrote:

> Too bad that link doesn't show just a plain 4 pin relay of the most
> common type and what I used. It shows two common versions of the 5 pin
> type, either of which would do the job if the 5th pin was ignored.
> Unfortunately, incompatible special versions of 5 pin relays also
> exist,
> such as in some Vanagons, so close inspection of the diagram printed
> on
> the relay would be required to prevent wiring it up wrong. Simpler
> just
> to get a generic 4 pin relay and not have to figure out which pin is
> the
> 5th pin odd man out.
>
> Mark
>
> Zeitgeist wrote:
>> http://www.the12volt.com/relays/relays.asp
>>
>>
>> On Wed, Aug 21, 2013 at 3:48 PM, mark drillock <mdrillock@cox.net>
>> wrote:
>>
>>> Almost, the trigger is a ground from the horn button.
>>>
>>> The power line to the horn gets split off to also feed 86 of the
>>> relay
>>> trigger, constantly. Then 85 is wired to the horn button wire and
>>> the
>>> horn button grounds 85 when pressed. So the button ground is the
>>> real
>>> trigger.
>>>
>>> Mark
>>>
>>>
>>>
>>> Jim Felder wrote:
>>>
>>>> So, big 12v wire straight to the horn, big ground wire interrupted
>>>> through the relay at  85 and 86, with the trigger and ground as
>>>> usual?
>>>>
>>>> Jim
>>>>
>>>>
>>>> On Wed, Aug 21, 2013 at 5:17 PM, mark drillock <mdrillock@cox.net
>>>> <mailto:mdrillock@cox.net>> wrote:
>>>>
>>>>     Yes, the relays with a mounting tab can be handy, like the
>>>> one in my
>>>>     photo has. Your description of your use of pins 85 and 86 is
>>>> not
>>>>     what I did at all for the horn usage though. I guess I will
>>>> post
>>>>     more details about the relay wiring at a later time. Because
>>>> it is a
>>>>     horn circuit we are actually using the relay for controlling a
>>>>     ground wire after the horn rather than the more common usage
>>>> for
>>>>     controlling a power wire before the power consumer.
>>>> Electrically it
>>>>     amounts to the same thing but people visualize it differently.
>>>>
>>>>     Mark
>>>>
>>>>
>>>>
>>
>>
>> --
>> Casey
>>