Hello:

My S40 2.0 COMFORT 2012 has a third brake led light. When light the led are dimmed. At night are seen a bit low as the common rear lights, In the day are too poor.

One- I do not know if it is a ground contact problem, where, or a defective fuse.
Two- Maybe I must replace it, but how is it?

Regards

 

have you done any probing with a volt-ohm meter? I'd start by unplugging and inspecting connectors/cleaning up or scuffing up the contacts. From that point you can also probe to measure voltage and resistance to ground. You should also check a wiring diagram to see if the CEM is in the circuit path for the brake lights and you may want to check the pedal's switch as well.

 

I think it is the LED Light only, becase all other works fine