Auto lights retrofit on pfl mk 2

Hi all,

Was looking to retrofit the above and thought it were a case of running a repair wire from the switch loom to the bcm (have all the sensors etc it's the one wire that needs adding) but didn't realise the pre-facelift is different to the facelift in terms of where it needs to go! What do I need to be looking for location wise to get this wire added in to? (if it can be added in this way).

Cheers!