The horn relay is nothing special, just a generic "bosch style" 4 pin
relay. Every VW has a couple and many other cars do too. VW refers to
this one as Type 53 or 24 and stamps that number on the top in big type.
You can buy the generic version at any flaps, often sold as a fog light
relay or horn relay, or driving light relay. Commonly used as fuel pump
relays as well, as in Vanagons. Typically 30 amp, sometimes 20 or 40
amp, all more than enough for horn use. Sometimes the generics have a
5th pin that isn't used for what I did.

The 4 pin relay has pins labelled with numbers and is used thus:

30  load in
87  load out
86  relay control input pin
85  relay control ground pin

Mark

Marco wrote:
> Thanks for the tips, Mark.  I have ordered one of those Hella horns from the eBay vendor.
>
> Do you have a part # or source for the relay? I couldn't find it in the archives.
>
> Thanks,
> Marco in Seattle
>