Question: DIY footwell lights with LED strip

[DV52]

DV52: Does it means that I can't simply fit a fog light by connecting the wire to the existing rear fog light of my car?

LMF: hi again. The fact that you have asked this question makes me believe that my first response was confusing. Please accept my apology for not being clearer.

The point that I failed to emphasise in my previous response was that I didn't think that you could take the supply wire for your LED footwells from a fuse position. But you could source this wire from any point in the existing footwell loom (inside the cabin). Also, if you want to change from an incandescent to an LED, then you may need to consider the possibility of error messages from the BCM (as suggested in mattaus's post) - but this really depends on the type of LED (i.e. how it is manufactured) and whether you leave the incandescent connected. If you do get errors, then my table may be of use

Same applies to the addition of a rear fog light. I have enclosed below my version of a wiring diagram for the rear fogs on a mk7 (showing the BCM connectors in this case), which I hope is of help.

As can be seen, VW simply connect the second rear fog in parallel with the original unit (which is what I suspect that you want to do as well). Notice also that there are no fuses in the circuit (like the footwell lamps). On the factory fit-out, the position of common coupling for the two lamps is a connector that is mounted on the rear lid, but it's probably easier to simply run a wire straight across the back lip of the tailgate as a retro-fit exercise. You also have two alternatives for fitting the new globe; you can either drill-out the blank part of the no-fog-light assembly, and force-fit (or glue-in) a new lamp holder, or you can buy an entirely new fitting that has the fog lamp base already installed. So no problems with the physical install.

The only other consideration is the programming side of the solution (i.e. will you be converting to LEDs and/or how is the Leuchte-set for your rear log light currently programmed). But this is not a difficult issue to resolve - just let me know what (if any) error messages you get and I'll try to help. If I don't have a solution, then I'm sure that other more experienced folk here will be able to find a fix! That's what forums like this are all about!

Cheers
Don