A8 issue under hard acceleration
 

Hey everyone,

Has anyone ever seen this behavior?

After a few seconds of accelerating the car hard (not full throttle) from a stop the red dashboard brake light starts to flash and beep intermittently and randomly for about 5 or 6 seconds then stops.

This is strange behavior. Someone suggested it was traction control, but that doesnt make sense.

Anyone have any clue why this is happening?

I'm no expert, but traction control might not be a totally senseless answer, the control works by applying brakes to any wheel that slips, thereby transferring drive to the opposite wheel. Might be worth looking into.

It doesnt make sense for a couple of reasons:

- the light and beeping start about 5 seconds after the acceleration starts. Wouldnt it sense it right at the start when the torque load is highest?

- why would the car announce wheelspin with a beeping brake light?

- why would it keep flashing and beeping when I stop accelerating (the first time this happened I lifted off right away and it kept happening)

Mongo has a good point...especially if there is a fault in the ESP. It can light up a brake warning, abs warning or ESP (traction) light.

Check your brake fluid level too...if low, acceleration will shift it enough to trip low warning.

What year/model car?

Describe light and exact location...

...Where is the light on display? ...the word "brake" (like when parking brake is set) or a symbol.

P.S. If ESP malfunction, it can set one of those lights AFTER detecting problem.

When the warning continues, the system is telling you that subsystem was deactivated (temporarily?) because of the problem detected during ESP intervention....straight out of Audi's tech training manual.

It will show in the fault memory, with Vag.com code check.

'07 A8

The light is red, and read the word "Brake" written out and is in the center of the MPH gauge


I thought ESP had its own light on the dash?

One self-test you could perform would be to turn off the ESP and accelerate hard...if no warning, try it again with ESP on.

So an error in the ESP intervention is triggering the red brake like?

Any clue what the cause may be?

Excellent idea.

Will try and report back...

It does, but like I said, if a subsystem fails during ESP operation, it tells you which system failed...no matter what caused it...the ESP, the ABS or the brake circuit itself. Doesn't necessarily mean that the brake itself failed, but something caused that part of the process to fail.

Don't forget to check fluid level, especially if light still trips with ESP off.

Will do

Possibly.

And if it IS an ESP problem, acceleration tripping it could point to EDL (rear electronic differential lock), which is aided by the spinning tire being braked individually...which could be hindered by a failing ABS sensor (or something else) at that corner.
That's just a guess.

Another possible cause is usually tripped during braking....failing EBD (electronic brake pressure distribution) preventing overbraking of rear wheels before ABS kicks in.

Some of this depends on specific ESP system in your model...more than one have been used in different models (don't know years/model?) with same functions, but different warning patterns. If problem persists, you need a code read by Vag.com.

Just wanted to follow up with the thread. Strangely I cannot repeat the issue. I'll post back if I can get it to happen again.

Did you top off your fluid and now you cant repeat the issue? Or did it just randomly stop happening.

I have an 04 that is doing the same thing. I havn't gotten to adding more brake fluid yet so I'm not sure what will happen.

A8 W12 brake warning light under acceleration
 

Did you figure out the solution?

I have exactly the same problem in my '05 A8 W12. When I accelerate hard the brake warning light flashes and beeps in the secondary MMI display, and the brake warning light in the speedo comes on. Stops as soon as I throttle back.

^^^

Regarding brake fluid, I have not had a service recently so have not tried it.

I have not solved it, wish I did.

I had originally reported I couldnt repeat the issue, but I do now still occasionally get the same behavior I originally reported and you also report.

I have the same issue on my 04 A8L. Anyone run the Vagcom on this? I will be ordering mine soon so until it arrives, if there is any new info on this, please post it.

Thanks.

Top off the brake fluid. The red "BRAKE" light is for fluid level low warning. It beeps and flashes to get your attention. The ESP/ABS will disable itself if it sees low fluid constantly, only as a default. Also, good idea to have a look at your brake pads. As they wear and the pistons are further extended, the brake fluid level drops in the reservoir.

I can confirm aspen79's post. I topped up the brake fluid (although had trouble seeing whether it was low or not) and the problem vanished.

04 had same problem. think brake fluid low. change all my pad doesn't do it anymore.it was annoying. i think when brake pad thin more fluid goes into line to make up for brake piston being push out more and more.

Hello everyone,

I originally started the thread.

The problem started popping up again, and I mean ALL THE TIME.

Turns out the suggestion about brake fluid is right. I added some DOT 4 and immediately the problem was gone. I can accelerate as hard as I want and the car won't do it anymore.

Brake pedal stiffened up as well.