I am reviving this topic, as I just activated the feature on my Astra (2005) using a Tech 2
As I was shown by the friend that actually did the activation, afterwards the feature can be enabled/disabled using the following procedure:
- turn off headlamps (from the switch left from steering wheel)
- start engine (headlamps will go on, this is daytime lights)
- switch on and then back off the headlamps from the switch mentioned above
Be aware, in Tech2 there are 6 configurations for this feature, disabled and enabled 1 to 5. It depends on which configuration you have this feature enabled, we tested all of them, and activation/deactivation procedure works only on the last one we tried (Murphy rulez....)