Tail Lamp Bulbs question
 

2005 X5 3.0i

Manual says #3 is backup lamp. What about the section under #3? Should any part of the red reflector light up when braking?

Rear fog lamps. Not equipped in the US.

Then can be retrofit for about $100 and one line of coding in NCS Expert though (mine are active), you need a European light switch to have them operate like factory.

I see. But shouldn't any part of the red reflector light up for braking as in other cars?

No, the outer lights light up (#2 in your diagram) for brakes, and its a dual filament bulb so #2 and #4 are lit up in reduced brightness when the tails are on.

Rear fogs are only activated in Europe or when done so via coding and retrofitting in the US models. We only need one set of brake lights in DOT spec.

if the rear fog light is done properly, with individual leads to each fog light and the correct programming of the LCM, then if your regular brake or tail light is out, the LCM should (I say should, as I have not tested it myself, but i saw it in operation on somebody's car) activate the fog light to substitute the burned tail/brake light...

other than that - the cavity that your are pointing to is vacant in the US E53s, no light bulb in there

check this post, and might as well read the thread too...

http://www.xoutpost.com/943954-post200.html