[FujiRRSC]

Hey all,

Very concerned and having the car go into the dealership today. A few weeks ago on a road trip in heavy rain my brakes went out. Driving in LA traffic I went for the brake and the pedal went very hard and I could not push the pedal down but maybe a tiny bit. Car would not slow down either... Luckily, I was in the fast lane and able to ditch out into the emergency lane and coast to a stop. After setting the parking brake and restarting the car the pedal went back to normal.

Now today we are having heavy rainfall and had the same thing occur again except in a tunnel with no where to go. Luckily the cars in front were some ways ahead and I was able to start coasting to a stop. All the sudden around 30 mph they started working again and worked as normal until I could get to a safe place to stop the car.

My SA was surprised and has not heard of this before. Has anyone else heard of this or had any experience with this problem? 2012 RRSC 57,000 miles and had a full brake job a little under a year ago.

Thanks in advance.

 

[MARK_C]

No dash lights? Wild guess is something related to the ABS module blocking all of the ports to the brake cylinders due to a wet connector on the ABS hydraulic block itself.

 

[FujiRRSC]

No dash lights or any warning at all. Both times happened unexpectedly and then back to normal. That would make sense. Thanks for your contribution will run it by the service advisor. Will keep you all posted.

 

[rovingryan]

It is ok to pull on the parking brake switch to slow the vehicle. While rolling the brake will engage and if you release the switch while rolling it will release much like an old manual park brake. You will not harm the system at all and it is designed to work that way. It will also bring on the brake lights to notify the person behind you. Surprisingly the parking brake is quite effective at slowing it down. This feature worked on my previous lr3 and current rr.

 

[FujiRRSC]

*Update

Finally got the car back from the dealership today it was not due to rain just a strange coincidence. Per the service advisor "Verified customer concern, found connection from vacuum line to brake booster cracked. Replaced Vacuum line and connector".

Hope this helps anyone should they ever experience this.

 

[CJD]

I feel time for some teaching?!? I am sure you have wondered why the brake pedal on power brake cars is larger than on manual brake cars? It is so you have room to place both feet on the pedal and push like hell if the booster goes out. The point I am making is that you never lost your brakes...you lost your power system for the brakes. If you pushed hard enough on the peal the brakes would have stopped you just fine...but you must push VERY hard indeed! This is actually in every state driving education book I have seen.

OK, back to your regularly scheduled program.

 

[FujiRRSC]

Thank you and good to know! I guess I have been fortunate to have never driven a manual brake car or have anything like this happen. When it did it felt like they went out is how I described it. It is useful to know!

 

[CJD]

I have never had a booster go out on the road, but I have done dumb stuff in the past, like forget to hook up the hose after doing work under the hood. Your are right, when you push the pedal it feels like you're pushing an immovable object! I've practiced in the driveway, and my thought is always that I hope it never happens out in traffic. It would be disconcerting to say the least, and take a few seconds to regroup and get both feet on the pedal to stop.