LeftMidfield

I'm brand new to this (or any) forum - my apologies up front if my manners are bad.
I have a 2000 A4 2.8 Avant. I bought it new and love the car.
However, ~2.5 years ago I had a very bad experience.
I was on a 4-lane highway, going 60 mph, cruise control on.
Rounded a bend in the road and the cars ahead were stopped because
of an accident in the road ahead. I applied the brakes and the brake pedal
just went to the floor. No brakes. No resistance on the pedal except for the spring.
On top of that, the cruise control stayed on. I was really, really lucky in
that there were no cars in the oncoming lane so I blasted past all the
stopped cars at 60 mph.
The brakes still didn't work and the cruise was still on so I turned off the
ignition and the car eventually rolled to a stop (didn't think of the emergency brake).
After a little while I started the car - still no brakes.
Then I switched off the cruise control and about three seconds later
the brakes worked perfectly. No other signs of any problem whatsoever.
Took it to Audi service the next day and they were unable to duplicate the problem.
To make a long story short, I didn't use the cruise control for a long time.
Never had any brake problems. Every now and then, when there were no
cars around I'd try to duplicate the problem but wasn't able to.
Then about a year ago it happened again. Same thing - no brakes until I
turned off the cruise control. I'm getting ready to sell the car and really
need to resolve this problem. I don't want this to happen to anyone else.
Audi recently tried very had to diagnose the problem, free of charge, but
couldn't duplicate it.
Has anyone ever head of this problem?
Any guesses as to what would make the brakes not work with
the cruise on and then work fine after the cruise is turned off?
Audi probably thinks I'm nuts, but I assure this is 100% factual.
I could really use some help with this.

ImAwesome

there seems to be a repair for the cc module.. maybe it will help?<ul><li><a href="https://forums.audiworld.com/a4/msgs/2501398.phtml">clicky</a></li></ul>

Joey T

There is no way the brake pedal went to the floor and then came back.

I guess, if you are incredibly stupid, you could have held the brakes down until they overheated, and then let them cool.

If this is the case, I strongly suggest you take up very fast motorcycles.


That way you only hurt yourself.

ImAwesome

or in panic he could hit the clutch? (presuming manual)

LeftMidfield

Thanks for the reference, but the problem with my car is not uncontrolled acceleration/throttle. In my case the brake just did't work (at all) and the cruise just stayed on - until I switched off the cruise control. Then all was well.
Yes, it is a manual transmission, but I assure you I didn't hit the clutch by mistake.
I know, sounds impossible (but not).

Joey T

Other than a small switch for turning the cruise off, the two are unrelated.


There is no possible way for the cruise to effect brake operation. You may have to push harder, but the car will stop.

You are lying if you claim complete brake failure.

Charlie Brown 99

I had exactly the same problem happen to me yesterday. I have a 2005 A4 1.8T. I was driving with the

cruise control on at 70 mph. I hit the brake lightly to disengage the cruise and nothing happened. I

looked down at the brake pedal to make sure I was hitting it - it was going all the way to the floor

like it was completely broken. The car wouldn't slow down and the cruise light wouldn't go out. I hit

the clutch with my left foot and the brake with my right foot at the same time - NOTHING. I pulled over

onto the shoulder and cranked the emergency brake as hard as I could.

Would you believe at that instant, a car pulled right in front of me on the shoulder and slammed on his

brakes? I came within 2 inches of hitting this guy. I was frantically slamming the brake pedal up and

down to no avail; waiting helplessly for the emergency brake to slow the car which seemed like it took

forever!

After I stopped, the cruise light went out. I flipped the manual switch to turn the cruise off (which I

didn't remember exactly how to do while I was panicking trying to slow the car down at the time).

I then backed up slowly and tested the brakes. They worked. Then I went forward in 1st gear very

slowly and tested them again and they worked.

I continued to drive about 10 miles to reach my destination very slowly and didn't experience any more

brake failures. I DID NOT PUT THE CRUISE CONTROL BACK ON!

The dealer can't find anything wrong with the car!

I refuse to drive the thing.

1 1/2 months ago I was pulling out into 50 mph traffic from a dead stop. All of a sudden the car starts

bucking and looses power. I see a car behind me skidding sideways in an effort not to hit me because I

was going so slow. Apparently this little mishap was the ignition coil failing in one of the four

cylinders.

Now I've be in two life threatening situations with this car and it only has 33K miles on it. I've had every service performed on schedule. What's next, wait for the rest of the three coils to crap out whenever they feel like it? How about perhaps wait until the brakes magically decide to stop working even when the cruise isn't on????

I've heard from three towing guys that all they do is tow Audi's and Volkswagens!

Yeah, great German engineering!

cparke

Brake switch(es) probably going bad --- cruise needs to switched off by hand