X6 E71 CHMSL: The third brake light

[szulta]

Hi everyone
I want to ask for your help.
CHMSL: The third brake light does not work.
the led row is working from another power source the fuses are also OK.
What could be the problem? brake light controller?
Thanks

[wewin]

檢查看看燈座上面線路是否腐蝕了

[Steinnn]

On the E71 X6, the CHMSL (third brake light) is LED and controlled by the FRM, not a separate brake light controller.

Since the LED strip works on an external power source and the fuses are OK, the most likely causes are a broken wire in the tailgate hinge/loom, an FRM fault, or the FRM output being shut down due to a previous short.

Check for voltage at the CHMSL connector while pressing the brake pedal, inspect the tailgate wiring where it flexes, and scan the FRM for stored faults. If there’s no voltage and the wiring is intact, the FRM output stage for the third brake light may be faulty and would need repair or replacement.