Bugbyte72

Hi all, long time lurker, hope you can help. Brought an NX3 Towbar and electrics including a relay to fit myself. The towbar part was easy enough but I am struggling with the electrics. Does anyone know either a tow bar fitter in the Birmingham UK area that will just do the 7 pin electrics (it hasn't had the Skoda tow bar prep) or have any idea how to connect up the relay to the back light units. I have worked out the indicators but the lights / breaks are on a pulse modulator system (about 11.8v for tail lights and 12.3v for break lights on the same line) should in theory go to one input into the relay with the relay working out the correct output signals. However, this does not appear to work! Thanks in advance for any replies!