Third brake lamp malfunction

[Mr.M]

Hello!
My car is w204, C250CDI, 2009, sedan.

The 3rd brake lamp (the auxiliary stop lamp) has a malfunction. Sometimes is working perfect, sometimes not. The LED bar is fine, the lamp contact is ok. Also the rear SAM seems to be allright.
What else can I check ?
I suspect a relay, module, fuse or an imperfect contact. But which one?
Where can I find the schematics for electrical circuit of the auxiliary stop light (3rd brake lamp) ?
Thank you!

 

[television]

I would say a broken wire in the hinge area.

 

[Mr.M]

Thanks, Malcolm!
The wires in the trunk area are fine. I want to check all the way but I do not know where they come from: under the dashboard, swich pedal, trunk(back SAM), front SAM....
An electrical sheme would be very helpful but I can not find any...

 

[television]

The third high stop lamp is usually wired direct, unlike the other lamps. I take it then that this lamp is in the rear window and not in the boot lid.

 

[Mr.M]

Yes, this lamp(LED) is in the rear window and as I see in the datacard, it is an "ADAPTIVE STOP LIGHT FLASHING". The circuit for the 3rd brake lamp has a relay or a fuse somewhere? If it is wired direct, from where it starts? from the brake pedal?
Why the rear brake stops are working fine and the 3rd brake light not? I think the brake lights circuit is shared by a point . Where it splits? (for rear brake lights/3rd brske lamp)

 

[television]

The 3rd lamp should be independent of the others as a safety thing, it does share the pedal.

 

[Mr.M]

I solved the problem by changing the lamp.