I have an '06 R53 that had the cover on the rear bumper where the fog lamp would go (US car). Under the cover is a plug, so I bought a clear fog lamp from Way Motor Works, put an led bulb in it, and and plugged it in. The wires going to the plug are brown(negative) and yellow with a brown stripe. They enter a loom that runs across the back bumper and then they go up the passenger side, terminating at the row of toggles on the dash. If you didn't get the rear fog as an option (not sure if any US cars did), there is a blank in place of one toggle, so the wires aren't connected to anything. The easiest place to access the wires is in the rear cargo area. Remove the passenger side access cover, remove the black fabric tape the wires are wrapped with to the point where you can find the ones you need. They are the aforementioned yellow with brown stripe and blue with a yellow stripe (passenger reverse light +). Jumper these two together with a quick splice connector, wrap the wires back up with electrical tape, replace the cover and you're done. Note: I replaced the incandescent bulbs with Napa's house brand led's. It's not dark yet, so I can't comment on brightness, but I will update. If anyone has found an led in these sizes (the small reverse bulbs in the tail lights and larger one in the rear fog light) that you have found to be bright and reliable/durable, I'd love to hear about them. I tried the larger Napa led in the turn signal and it was a no-go...started flashing double-time. My next project is replacing the fender clearance lights with led units...wish me luck.

 

I added a rear fog to my 06 last summer with the factory full toggle panel. Unfortunately you need full toggle, rear fog light and the dealer or Way program the ECU for you for it to activate the circuit. It was easy peasey but you need the factory programmer from what I understand. Good luck.

 

So the blue/yellow wire powers the reverse lights in the taillights? My car is an 03 so I already have the reverse light you just activated -- the taillight housings have sockets for rear fogs. Enabling them is (way down) on my to do list.

 

I added rear fog on my 04 R50. I got the complete switch bank with rear fog. Then I just used ncs expert an activated rear fog option. Was super easy.

 

The center fog works as a reverse light when you connect it to a reverse wire. The one going to the passenger side tail light works best because the fog wire is in the same harness. Working great so far. It doesn't seem to give the computer any problems. I am able to see much better backing up at night, so mission accomplished! I'm going to do the clearance lights today.