I had the exact same problem.
Took the steering wheel off and cleaned everything up.
Turns out the shavings from horn ring had collected and formed basically a
new contact.
Hasn't happened since.
Photos here:
http://picasaweb.google.com/T3Vanagon/SteeringColumn#5341075424314685746

On Wed, Oct 28, 2009 at 3:22 PM, John Rodgers <inua@charter.net> wrote:

> Well, Volks, it appears a Horn Gremlin has taken up residence in my 88
> GL. Now when I drive down the road, the horn just sounds on its on,
> whenever it pleases. It seems to be related to movement of the steering
> wheel. Move the wheel, blow the horn. But not every time.
>
> So, Volks, what say you? Ideas??
>
> Thanks,
>
> John Rodgers
> 88 GL Driver
>
> --
> John Rodgers
> Clayartist and Moldmaker
> 88'GL VW Bus Driver
> Chelsea, AL
> Http://www.moldhaus.com
>

--
Drew, Las Vegas
'90 GL "Blackbeard"