Phantom stomp on brakes?
 

My A6 wagon has twice in one year experienced a sudden jolt and what seems to be a brief but completely unnerving braking of the wheels (with foot nowhere near the brake pedal) for no more than a second or two. Any clues out there? Scares the living $#!% out of me and makes me wonder about taking the kids in the car.
Thanks in adv.

I never had that happen to me and it would scare me to death as well!

What year and model is it? In what kind of time frame did it happen and what kind of weather condition?

The only thing I could remotely suspect (but I'm no expert): Could it possibly be some issue with the ESP/ABS module?

Thanks, Sheldon. Its an '02 A6 wagon with the 3.0 non-turbo. engine. Both times I believe it was raining. I think the involuntary braking (or whatever it was) seemed to be accompanied by a chattering noise that sounded almost like it was behind the dash. Its hard to say for sure as this happens in a second or two and is gone. The first time also lit up that traction warning light (the triangle with exclamation point) on the dash, but went out after I pulled over and restarted the car.
Would love to know what is going on.

I hope we have a few experts that can jump in and give some valuable information to you how to address this issue.

Since you mentioned the warning triangle and the shuttering noise I lean towards the ABS control module. That thing has a reputation to go faulty and usually it just lights up the ABS and ESP lights while driving (which means they stop working) but that thing does control the brake system to help you have control in slippery conditions.

If this module is indeed the cause, get it rebuild for 300-500 bucks with a very good warranty @ ModuleMaster | Services | ABS Modules (5 year warranty)
or if you have too much money (some people do have that :P ) you can buy a brand new one between 900 and 1300 bucks with only 1 year warranty.