TravelMore

Hello,

The other day I was stopped at a stoplight (pointed slightly downhill) when suddenly the brake pedal depressed all the way to the floor. I hadn't increased pressure on the pedal, it just sank down suddenly on it's own. When the light turned green and I removed my foot from the pedal, the pedal stayed depressed and pressing on the gas pedal didn't make the car move forward despite being pointed downhill. I put the car in park, turned it off, turned it back on, and the brake pedal returned to its normal position and normal pressure. Does anyone know what would have caused this? The car is used and has about 33,000 miles on it, so I don't know if the brake fluid was replaced at 30,000 miles or not. I also didn't notice any lights on the dashboard, but I was pretty distracted with all the cars honking at me when the light turned green so I could have easily missed a warning light.

Any thoughts or suggestion would be helpful,
Thanks!

no1SomeGuy

Malfunction of the brake booster maybe? Something in relation to the Hold function? I would be taking it in to a Lexus dealer for an inspection though. That is rather strange behaviour, usually a pedal sinking to the floor would indicate a loss in brake pressure due to a fluid leak but turning on/off restoring it to normal is strange unless related to the brake booster (which is powered by engine vacuum). Regardless I'd consider this unsafe behaviour and wouldn't be too keen to drive the vehicle until addressed.

pbwillz

Does your brake pedal feel spongy when you press down on it? Brake pedal depressed too much or goes down to the floor are symptoms of air in your brake lines.

I would start with bleeding your brakes. Most likely won't be covered under warranty since this is considered wear and tear.

It can be done by yourself or easier if you have a friend help.

no1SomeGuy

Disagree with this take on it...air in the brake lines doesn't manifest as a sudden drop in the pedal once already stopped.

TravelMore

Update: I took it to the Lexus dealer and they ended up replacing the brake actuator (the vehicle is 40 months old so it's out of warranty, but Lexus covered it at no cost). I'm not sure they the actually identified the exact problem so much as narrowed it down to the most likely culprit and fixed that. I haven't had any issues since, so fingers crossed it was the correct solution!

RXWes

The Lexus warranty should be 48 months or 50K miles.

www.lexus.com/warranty

dcrandall

Question, were you getting a strange sound from the actuator or your breaks prior to the failure? When i brake at slow speeds i get a strange sound every time. Im thinking its the actuator. Took it to the dealership but they couldnt replicate the sound.

nickage87

I think I have the same thing. Sudden sounds when applying break pedal. Sometimes it feels too soft and I am able to push it all the way down with not much force. But dealer could not replicate the sound.