Third Brake Light [Archive] - Audi Forums

: Third Brake Light


gio64
12-07-2011, 09:20 AM
Hi, I tried searching, but I don't get any information.
I have a 2002 A4 Quattro 1.8t.
The dashboard indicator complains about the third brake light (or centre brake light) having a problem. The LED set works flawlessly. So do the rest of the brake lights.
I have not replaced any brake lights recently.
This problem has started after we changed the steering rack.
It also came with the stereo refusing to work (that's an altogether different story).
If you have any info, I would really appreciate your help.
I tried to disconnect and reconnect, I took the light out and checked it while out to make sure each and every single LED worked. They do.
Thank you.

mullardel34
12-08-2011, 09:29 AM
Are there any DTC fault-codes logged in the ECU? The Audi ECU will log fault events, but if the faults are not mission-critical in nature, the dreaded "check engine" light may no be illuminated.

Hmmm... if the problem began around the time of the steering-rack replacement, the only brake-related component that might have been damaged (at least, that I can think of...) is the brake-light switch (located in the pedal-cluster). The brake-light switch tends to be rather fragile and the switch is one of the sensor inputs for the ECU system; intermittent switch failure can prompt the ECU to incorrectly determine that the Audi B6 A4 is experiencing a number of braked-related faults. Fortunately, the brake-light switch is inexpensive (Audi B6 A4 Quattro V6 30v > Search > Brake Light Switch > ES#1077363 Brake Light Switch - 1K2945511RDW (http://www.ecstuning.com/Audi-B6_A4-Quattro-V6_30v/Search/Brake_Light_Switch/ES1077363/)) and fairly easy-to-replace.

Just a thought... :cool:

gio64
12-08-2011, 09:57 AM
Are there any DTC fault-codes logged in the ECU? The Audi ECU will log fault events, but if the faults are not mission-critical in nature, the dreaded "check engine" light may no be illuminated.

Hmmm... if the problem began around the time of the steering-rack replacement, the only brake-related component that might have been damaged (at least, that I can think of...) is the brake-light switch (located in the pedal-cluster). The brake-light switch tends to be rather fragile and the switch is one of the sensor inputs for the ECU system; intermittent switch failure can prompt the ECU to incorrectly determine that the Audi B6 A4 is experiencing a number of braked-related faults. Fortunately, the brake-light switch is inexpensive (Audi B6 A4 Quattro V6 30v > Search > Brake Light Switch > ES#1077363 Brake Light Switch - 1K2945511RDW (http://www.ecstuning.com/Audi-B6_A4-Quattro-V6_30v/Search/Brake_Light_Switch/ES1077363/)) and fairly easy-to-replace.

Just a thought... :cool:

Thank you so much, I'll have a look. Would it show signs of problems, or should I just get another one?
Giovanni

gio64
12-08-2011, 12:38 PM
sorry, I forgot to answer to the first part of your post.
I don't have a scanner I can do that with, so I can't say. I am thinking about getting something, but I haven't decided yet.

mullardel34
12-08-2011, 01:42 PM
If you're located in the US, most of the major auto-parts stores (Advanced Auto-parts, AutoZone, etc.) offer to download all OBD-II fault-codes for free with a scan-tool. I'm not aware of any equivalent service outside of the US. ;)

There's really no means to visually assess the viability of the brake-light switch; if it's suspected of being faulty, it's best to just get a replacement... :D

Good luck! :cool: