A4 B6 Brake problems

[Martin Johan Vean]

Hi,

Feel like I should mention that I have no experience working with cars, since I got my license just a few months ago, and this is my very first car.

Here is the story so far;

Recently I started having problems with my car. The ABS and ESP lights came up while I was driving. I drove home and told my dad. A friend of him came over to run a diagnostic (I think he used a vag-com, not to sure) and the only fault he could find was a problem with the brake switch. We replaced the brake switch, but the problem still occurred. Some time after my second problem began, the brake lights seem to be illuminated most of the time while driving.

We did not know what else to do so we took the car to a repair shop. They scanned the car and just found the same fault with the brake switch. It was replaced again, but the ABS and ESP lights still came on with the brake lights illuminated. They checked a bunch of wiring leading to the back of the car. The previous owner had done a lot of weird stuff to the wiring, I was told. They replaced all of the wiring so it could be like it originally was when the car was made. None of the problems was fixed by this. They scanned it again multiple times and the brake switch was still the only fault they found. They were not able to delete the fault either.

My car have been at the repair shop for the last week and I got it home today. The mechanics said they were unable to fix this since they did not understand what was causing the problem. I did not have to pay for the "repairs" since they admitted that they couldn't do anything with it.

(I should also mention that sometimes I can drive for some time without any problems! Traction control working, and ABS working. Then I could brake to slow down and when releasing the brake, the warning lights come up combined with the brake lights staying illuminated.)

I don't know what to do and I feel kind of lost. That is why I found this forum and created this thread to seek help. If anyone have experienced something similar, or have any tips on what the issue could be, it would be greatly appreciated!

 

[pauldazzle]

The brake switch is a fit once device, & if not fitted correctly it will break.
Very important when fitting the new switch into the mounting that it makes a loud click when rotating it into position if it doesn't click it will break the first time you press the pedal.
I would suggest you buy a genuine VAG switch, & try again.

 

[Martin Johan Vean]

The brake switch is a fit once device, & if not fitted correctly it will break.
Very important when fitting the new switch into the mounting that it makes a loud click when rotating it into position if it doesn't click it will break the first time you press the pedal.
I would suggest you buy a genuine VAG switch, & try again.

Thank you, I will try one more time to replace the brake switch with a brand new one.
Also, I don't know if it is related to my current problems, but the car has not been used since I drove it home and the battery seems to be drained when I tried to start the car today.

 

[Martin Johan Vean]

Update: Carefully replaced the brake light switch, the car worked perfect for about twenty minutes until the ABS and ESP lights showed up again. Went back to my local repair shop and they don't know what to do and won't take the car in.
I don't know what else could be the problem.

 

[Ralphthemouth]

I know it's not especially helpful, but when the battery gets low it causes abs lights to come on. Have you checked all the earth leads? I presume when you said they couldn't clear the fault, so everytime you check vag com it'll say the same fault surely? Have you tested the outputs on vag com of the braking system? It'll all points to classic brake pedal switch faults, but I've that's been changed 2 or 3 times and it's still failing maybe it's getting too much power? All fuses and relays checked? Again, not much help I'm afraid.

 

[Retroman]

I agree with the post above. ABS is one of the features shut down when a battery is failing and the ECU reserves power for essential "drive home" facilities.