This is not "free", but at $7-$10 per hour, it is cheaper than a single hour of dealership labor. For a weekend DIYer who needs 15 minutes to download a wiring diagram, the effective cost is negligible.
Because erWin allows unlimited downloads during an active subscription, resourceful vehicle owners can legally obtain all the manuals they need for under $15 using the "One-Hour Flat Rate" method. vw erwin free access