Relay. It's a feature, up to some 1992 year, with wire, attached to alternator exciter wire, so, when engine is running, one touch up is on.
I'd like to put in my A90q one touch module from B3 passat, although that would require major wiring modifications and, likely, switch modifications - I have passat-like module in my mk2 golf, and I have one touch down for all windows - and since the module is protecting it's fuse by operating single window at once, it also has sequential window opening function, when, upon pressing all four switches, it will open windows in desired sequence
