A little expansion on FunJimmy's reply-
The stock Winker relay is electromechanical and relies on good voltage, either form the battery, or the stator when the motor is running. Modern Winker relays are electronic, and thus rely on lower voltages and can interact with LED winners by using an inline resistor, or diode, or other 3 prong relays.
Power to the stock relay is handled through the loom and you'll find it located under left side cover, round body device with little discernible info on it.
As for "separating the looms" this is actually done already for you somewhat by virtue of the fuse panel. The Main fuse powers the ignition, starter solenoid, and background circuits. The other circuits supply power to the headlights and Taillights (some difference in Euro spec models we didn't get here in the States).
You will also find the stock indicator and switch housings ground to the frame so bare metal is essential for proper operation.
There's a member, Deltarider, who's in Netherlands and has I believe a late model 500 (may be a 550) and is quite familiar with the idiosyncrasies of the Euro spec diagram changes. Hopefully, he will pop along, else you could send him a Pesonal Message thru the forum.
Cheers-