Most older VWs that I've seen do not have power to the horn when the ignition is off.  So there is a part of the circuit there.

The horn has +12V any time the ignition is on.  It works by grounding it through the contacts in the steering wheel.

Not sure this answers your question.

Allan

On Fri, 27 Feb 2009 07:43:58 -0800, "Rocket J Squirrel" <camping.elliott@GMAIL.COM> said:

> Howdy all, popping my head up to ask a question here.
>
> When it gets cold, say freezing or under, the horn honks when I jiggle
> the key. What's the physical relationship between the horn wiring and
> the ignition lock? And why doesn't this happen when things are warmer?
>