Unintended braking in reverse?

[kiznarsh]

Every once in a while when I'm backing up, the brakes suddenly kick in with barely any input from me. I can't re-produce it every single time, but it happens about once every 2 weeks.

When I'm backing up slowly with my foot slightly on the brake pedal, the brakes suddenly engage at 100% and surprise the hell out of me because it makes me think I hit something. [confused] I know it sometimes happens when I'm on a small incline out of my driveway, but haven't been able to repeat it.

Anyone else?

[audisarecool]

Every once in a while when I'm backing up, the brakes suddenly kick in with barely any input from me. I can't re-produce it every single time, but it happens about once every 2 weeks.

When I'm backing up slowly with my foot slightly on the brake pedal, the brakes suddenly engage at 100% and surprise the hell out of me because it makes me think I hit something. [confused] I know it sometimes happens when I'm on a small incline out of my driveway, but haven't been able to repeat it.

Anyone else?

YES. happens to me every once in a while..makes a 'thud' noise too.

[ImolaMonster]

YES. happens to me every once in a while..makes a 'thud' noise too.

x3 - happens to me too! - thought it might be a loose rotor or something??

[sirpickles]

does the S4 have hill assist?

[brooklyn86]

does the S4 have hill assist?

Yes. The electronic parking brake acts as a hill assist.

Engage it while on a hill. As you try to move (in gear, let off the clutch and give it gas), the parking brake will automatically disengage when it senses you have enough force to move forward.

[dparm]

Yes. The electronic parking brake acts as a hill assist.

Engage it while on a hill. As you try to move (in gear, let off the clutch and give it gas), the parking brake will automatically disengage when it senses you have enough force to move forward.


Not all S4s have it. There's a particular code on the build sheet that denotes if you have it (AudiEnthusiasts.com has the details).

[kiznarsh]

The electronic parking brake acts as a hill assist.

Yeah you can definitely use that for hill assist, but in my scenario (and apparently at least 2 others), the brake has already been disengaged. But I wouldn't be surprised if it's an electronic glitch that's causing it. It seems like only the rear brakes kick in and IIRC, the parking brake is only for the rear wheels so...I guess it has to be an electrical problem.

[LYKUNO]

This almost sounds like the antithesis to Audi's famed issue of "unintended acceleration". I'm reminded of the 1980 Audi 4000 (automatic with 5 cylinder motor) that I bought from my brother back in the early 90s. It had a blown head gasket so he sold it to me cheap and I got it fixed up and we gave it to my mother-in-law to use. My father-in-law was up in years and was not a great driver, but he would occasionally drive "Mom's car". One day while backing it out of the garage, as he was looking over his right shoulder (he rarely used rear-view mirrors, and IMO, he accidentally shifted his foot from the brake pedal to the throttle), the car took off in reverse and he shunted it directly into a large walnut tree on the adjacent neighbor's property. He swore he had his foot on the brake though! That was the end of that Audi, at least from my MIL's perspective. They gave the car, which was still someway drivable, but with a bashed in rear bumper and trunk that wouldn't close, to some mechanic's kid. The in-laws have since passed on, but I've never forgotten about the Audi 4000 accident, or the time my FIL managed to hit the mayor's wife's car with his minivan, and then narrowly missed putting the van into a small lake - but that's a whole 'nuther story!