I normally use a universal relay which needs individual input wires soldering onto the various lighting wires. But for the car I pick up this week I fancy using a can bus connected relay which brings up the dash trailer symbol and alters other car settings when towing. Does anyone have any experience of installing one? Either VAG part or a compatible unit which does all functions. Is 8K0 907 383E the correct Audi part number for a B8.5?