The blue/yellow wire on 2006 - 2014 Classic models within the chassis wiring loom linking optional spot/fog lamps at front of car to the dash area is a standalone connection and therefore has in itself absolutely no connection to the PCB referred to above. It terminates in an eight pin connector with only two of those pins used, the second carrying a side light feed (red/orange) which I would ignore. It's perfectly safe to use the blue/yellow cable though but would recommend any conditional switching should be performed by an additional relay, in the case of spots triggered by the high beam feed (blue/white), in conjunction with its own selection switch and separate in line fused battery feed. I believe the PCB did provide conditional switching for front fog lights but suggest this is not used.
