02-24-2013, 11:05 AM
Location: Chapel Hill, NC
Join Date: Dec 2007
Mein Auto: 2007 BMW 530XIT
2007 530xi "Center Brake Lamp Malfunction" answer
I have obtained lots of good information from this forum, and wanted to share my answer for the "Center Brake Lamp Malfunction" error message.
The solution for the 2007 530xi wagon was slightly different from what I have read on other threads.
In my case, there was nothing wrong with Center Brake Lamp, which is a light bar consisting of multiple red LEDs, set in the rear spoiler on the tailgate. Instead, there was a short in the wiring harness that goes to the spoiler and rear window. After repairing/bypassing the short in the wiring harness, it was necessary to replace the "Noise suppression filter (center brake light)", which is located by the right rear speaker above the right rear headliner. This part cost about $50, and is referred to as Z13 on page ECL-40 of the Bentley Publishers' BMW 5 Series Service Manual.
It appears to be a common problem that the wires in the wiring harness to the trunk and tailgate rub together, or chafe, resulting in breakages or shorts in the wiring.
In the case of my 2007 530XI, this has resulted in a number of intermittent and permanent issues, including the rear window button, the defrost grid on the rear window, and the center or Auxiliary Brake Light.
Here are my notes from diagnosing the Center Brake Lamp issue. Part numbers and connector designations are from the Bentley Publisher's BMW 5 Series Service Manual.
The center brake light, officially called the "Auxiliary Brake Light (part number H34a)" was functional. 12v placed across connector X138 caused the LEDs in H34a to light (red).
I had also experienced intermittent issues with the Rear Window Button (part number S147a). Electromechanical clicks could be heard when raising/lowering rear window. (Window, not Tailgate)
The original wiring between the Red connector(X13914) on Noise Suppressor Filter - center brake light (part number Z13) showed less than 1 ohm resistance between the Brown wire (ground) and Black/Yellow wire (even though X138 connector was removed from the Auxiliary Brake Light.) Resistance would change as the rear window was lowered and raised. (Window, not Tailgate)
I assumed that this meant a short between Brown and Black/Yellow wires, and replaced these with a red wire and a black wire between connector X13914 (on the Noise Suppression Filter - Center brake light) and connector X138 (the center brake light).
That caused the “Center Brake Lamp Malfunction” message to go away, but the center brake lamp still did not light when the brake pedal was depressed.
I assumed that this meant that the Noise Suppression Filter (Center Brake Lamp) had been fried by the shorted wires.
This turned out to be the case. I replaced the part (Z13 - Noise Suppression Filter (Center Brake light)), and the center brake lamp currently works. It is possible to replace the noise suppression filter without removing the headliner, by removing the speaker cover, and using a torx bit and open-end wrench to remove Z13. It is a pain, and you need small hands.
As an added benefit, the Rear Window Button (S147a) works correctly as well (for now. )