Rear Bulbs

[A01]

Hi everyone,

 

I got my Citigo 1 year ago it is a 2013.  Now it needs a MOT.

 

Question on rear bulbs.

 

There are 2 rear light clusters and the number plate light. 
Each rear light cluster is essentially the same, same number of bulbs and same colours.
Indicator lights and reverse lights - no problem they all work
All other bulbs, excluding the aforementioned reverse and indicators, in the rear clusters are 3 bulbs in each cluster for tail/brake/fog. Looking through the lens I can see the 3 bulbs top,middle and bottom on each cluster. and they ALL have double filaments.


Tail lights 5W 3 on each side they all work - 6 lights

Brake lights 10W only the one bulb at the top on both sides works for brake - 2 lights

Fog light 21W Only the one bulb, at the bottom on the driver side works for fog - 1 light

Now then that leaves some bulbs which have double filaments which are not illuminating the 2nd filament. The middle bulb on both sides does not illuminate the 2nd filament.

The bottom bulb on passenger side does not illuminate the 2nd filament.

The bottom one passenger side could be fog but not working?
The middle ones on both sides could be brake but not working?

If they are not supposed to illuminate WTF have they double filaments for?

Any advice appreciated

Thank you for reading.

[Hyphons]

I imagine to cut costs for manufacturing, countries with LHD vehicles must have, at minimum, a LH fog light, likewise for RHD vehicles, they must have, at minimum, a RH fog light, hence the twin filament on the bottom left bulb, all 3 tail light bulbs share the same bulb type, P21/4W, again, I imagine this just cuts down costs at manufacturing as the same bulb can be used no matter where it is placed.

[A01]

Hi,  I believe brakes are 10w  only fogs are 21w

 

So what about the middle two , are they supposed to illuminate for anything other than tail?

 

Thanks

[oxonboxn]

I shouldn't worry too much about the reasoning behind the light oddities...my 2013 Greentech has exactly the same bulbs/filaments working as yours and has just passed it's 2nd MOT. I agree with Hyphons...economy of manufacturing - simpler and quicker to have all countries' cars with the same bulbs.