99 A4 1.8T Quattro. All my brake lights operate normal during daytime without the headlights on. When the headlights are on the center brake light also illuminates without stepping on the brake pedal. Once the brake pedal is depressed it gets a little brighter. Is this normal? I thought the center brake light should stay OFF at all times except when depressing pedal. Also, when I step on brakes the corner lights (yellow) come on. Sounds like I have some sort of problem, or do I? HEEEEEEELP before I visit the stealer.

 

Sorry I don't have an answer to your problem but you defintly have a wiring issue. Center break light should only come on when the break is pressed and the corner lights shouldn't.

 

This is unlikely to be the same problem, but who knows... My brake lights would intermittently stay on even if the pedal was not pressed. The dealer tried adjusting the switch on the brake pedal but no dice. Replacement of the switch corrected the problem.

 

Hey Thanks. The stealer won't provide much info without taking it in for diagnosis (scary). My first inclination was the brake light switch at the pedal, but that operates correctly during the day and does make it slightly brighter at night. The main issue is that when you turn the headlights on the center brake light also comes on (i.e. it is acting as a tailight?).
I bought this car used so there is no telling what has transpired. Possibility of wrong bulb types? maybe. I'll probably throw a switch on there and see what happens. Does anyone know if there is another electrical item involved in this circuit like a relay or controller? Anyways, thanks again.

 

Lazy dog is probably right then - the previous owner must have messed with the wiring. That indicates the likelyhood of repairs due to accident or other unfortunate event. If you get the dealer to work on the wiring it will cost a fortune. If you don't have the expertise yourself, I would at least get a local/backyard mechanic to trace the wiring and eliminate that as a cause before looking at anything else.

 

ok found problem. headlight switch has gone faulty. this caused the center brake light to come on when headlight switch is activated and also caused cruise control to cut off.

now to replace the headlight switch

thanks to everyone again

george

 

OOPS I got real lucky. While I was checking around to see where I could get the best price on a headlight switch I noticed that the rear fog light bulb was not coming on. I pulled the bulb holder and noticed that bulbs were incorrect type and one was missing. I replaced all the bulbs with the correct type and wattage and guess what - the center brake light problem went away. I had this feeling it may be something of the sort but I just couldn't believe that whoever had the car before was st---d enought to use the wrong bulbs. I guess thats part of the fun of buying a used car. The headlight switch may still be partially dysfunctional but that is a separate issue (the switch when turned on also disabled the cruise control, i'll check this next time out but hopefully this went away too).

Again thanks for everyones input. The new light bulbs I used were from Pep Boys Sylvania 7506LLBP (P21 watt) and for the rear fog light 7528BP (5watt).

 

Yeah i've heard of people using double filiment bulbs when they shouln't and it causes strange problems like yours.