Could have something to do with the parking circuit. It uses a different circuit to park it, when the relay switches off, it uses a different 12V to ensure that it parks properly (bit confusing) could be that once the rel;ay clicks off, normally engaging the park circuit, it doesn't engage the parking circvuit, hence it stopping? Son't know if this is the way it works in Golfs, but i know a lot of old cars used to do this, they probably changed it now to something digtal...