Rear lights question

[Themoog2]

The other day we were driving in convoy from Carfest and when I got home the wife asked if I had my fog lights on.
This was also mentioned in an mot a few years ago and I think I may have posted about it on here.
Are the rear lights a bit odd ie the same bulb does lights and brake light or something like that. Can someone elaborate.

[X5Sport]

If I remember correctly, the fog light is in the light cluster mounted in the tailgate. The brake lights are in the wing cluster, and there should be two each side. The upper one works under normal braking but if you need to jump on the brakes then the lower ones also come on. Not sure if they flash as they do in later cars.

[Themoog2]

I've done a quick search and the rear bulbs seem to have 2 elements in them so I think that one is on and then the other comes on when braking. Maybe.

[X5Sport]

Pre-facelift (2003) the bulb will be a twin filament 12V 21W/5W. From LCI onwards all the rears are single filament 12V/21W.

Maybe the wrong filament is getting power? Can happen with a brake light switch fault, but then you should also see the 3rd brake light showing.

[marti]

The twist in bulb holders in the e53 are always a dodgy component...when changing a bulb always sand the two little sprung connections to get a good contact...another interesting thing on the e53 is if your angel eyes go on one side, on the side they fail the indicator comes on permantley on that side..until you replace the angel bulb

[henrym3]

Mine has a permenant fault when scanned reference the brakes. ie BFD for brake force display which seems to have been put into the ECU but not fitted to the vehicle. So when hard on the brakes I just get "normal" brake lights, no flashing brake lights or extra lights and definately doesn’t drop an anchor out the back.