eCoastAudi

It took me a bit more time than I care to admit.

Kept getting 00526 - Brake Light Switch (F) VAG code along with the BRAKE LIGHT error message in the display. This is a manual transmission car ('01 2.7T) so the issue with the false 00526 code with Auto trannys is not present. All lights work, all fuses were OK. Replaced Brake Switch F, nothing changed. I could see the bits changing in the measurement block 066 so wiring and ECU are OK.

Clearing the code would work until the brake pedal was pushed or released. Also, and this turned out to be a hint, the code would re-appear when the headlights were turned on.

eCoastAudi

Turned out the PO installed a one filament bulb in the left side dual filament taillight/brakelight position. This had the effect of joining the brake light circuit and the tail light circuit at the positive nub of the single filament bulb. (The nub is the right size to bridge the two contacts in the socket).
So the bulb works when either the brake light or the taillight is on but the ECU detects current in both circuits when it should be in only one and throws the Brake Switch code.

e292644

Thanks, I've got the same code and couldn't find the problem. Will check out these bulbs tonight.

jhuffman

lol fail on part of changing the brake light. You'd think you'd check the bulbs visually first and foremost just to see if they are the same