Enter VCDS-Lite 1.2. This older version of the software was the last major release designed specifically for legacy serial interfaces. For owners of older VAG cars (pre-2006) and cheap cables, it is a vital tool. But even this version requires registration—a "dongle" verification—to function fully.
: Install the specific drivers for your third-party USB interface (this is the responsibility of the cable supplier). vcds lite 1.2 loader