MikePalm

My 2007 RX400H has a serious brake problem. The regenerative braking doesn't work anymore. Its similar to the normal problem that you feel a surge when braking over a bump on a hill but much worse, and every time you push the brake pedal. When I push the brakes the needle goes into the blue area on the gauge for max 1 or 2 seconds, usually just a split second...then you feel the brakes let up and switch to regular breaking....sometimes pretty violently. In the past month I have gotten the regen brakes to work only a couple times where I can actually hear them working and the needle stays in the blue more than a second. I took it to Lexus and they said there are no codes and their tech admitted there is definitely something wrong but he has never experienced it. Now they are awaiting word from Lexus headquarters in Sweden about what to do.

Anyone know what this might be? My closest Lexus dealership has been waiting for over 2 weeks now and haven't heard anything from the headquarters what to do...meanwhile I am using up my regular brakes too much and my wife is scared to drive.

All hybrid components have an extended warranty to 200,000 km (at 195,500 now) or 10 years so I should be fine there, just hoping somebody knows what it is so I could point them in the right direction.

Thank you!

Caprica

Have you tried running around slow and giving your batteries a good drain, until they're showing in the pink/purple range and then taking it up to highway speeds and trying to regen? My regen doesn't do much once the battery gets to that second to last line and turns green on the screen. If something is wonky, maybe the controller thinks the battery has a full charge and won't let the regen operate, so draining it to the point that the engine kicks on to recharge might kick things back in gear. Worth a shot anyway.

MikePalm

Been driving for over a month like this...low battery, full battery, city, highway, hard, gentle, and everything else. I think even if the computer thought the battery was maxed out it wouldn't let the violent switch occur. It never happened in 2 years driving it before this happened. The lexus tech drove it for 2 minutes and said something is wrong but he didn't know what. I also took it to Toyota who said maybe a wheel bearing or rusted brake pads, but I really doubt that...they also added that they have never encountered the problem on any toyota or lexus hybrids. Thank you for your reply I will try to drain it the next time I'm driving and see what happens.

litzdog911

The Lexus tech didn't know what is wrong? Isn't it their job to figure that out for you?

lexusisgs

I had problem like that after we replaced rear wheel bearing on gs450 .ABS sensor was not reading bearing ring it was rusted too couldnt get out .so we had to cut it out piece by piece.
Order new one over web because dealer wanted $400 about and on web was about $30 but u have to wait couple weeks for delivery.
ABS,VSC light was on and no regn.braking available.
After we have replaced sensor everithing was back to normal.

MikePalm

Thanks for the tip about the abs sensor lexusisgs....considering i did replace the left rear wheel bearing a while back maybe it is related to that. I don't have any warning lights on or codes, though.

An update on the car. Lexus went through all the parts of the braking, replacing the front pads that got totally worn down from having to work too much, and came to the conclusion that its not a mechanical problem. They took a video of the gauges while driving to send to headquarters. The power needle will head down towards the blue area just for a split second. The regen brakes barely even try anymore so there is no violent switchover anymore, just a light bump feeling.

Now I have noticed that the electric motors do less than before. As soon as I put any pressure on the gas pedal more than the absolute lightest touch, the gas motor comes on right away. I used to be able to drive around at low speeds with only the electric motors much more than now.

The Lexus dealership determined that there is no mechanical problem 1 month ago and I have not heard back from them. They say to keep waiting for an answer from headquarters.

Caprica

Well if you are not getting regen and now not getting electric motor assist, it would seem to me the actual hybrid controller is failing in some way. What worries me is that this may end up causing your Lexus to not work at all if the controller is failing because it may end up not being able to power the small electric motor that makes the gas engine fire. It's still an amazing piece of engineering that a rig can work with 3 different electric motors and a gas engine to get you down the road and all 3 electric motors operate independently from each other and from the gas engine.

smassey321

Have they checked the brake pedal position sensor? Hopefully it is something simple like that. Best of luck

MikePalm

They had it over a day and said they checked everything mechanical. I was stomping on the brake pedal a little....it has always made a slight ticking noise, but if I push hard it will make the barking noise and some air whooshing noises. I mentioned this and they didn't seem to think anything was wrong. I know the actuator can make some noise and the ticking has always been annoying, so hopefully they replace it if they ever can start fixing it.

I have requested a loaner car now through swedish headquarters until they can figure out the problem so I guess we'll see how good the Lexus customer care really is. As Caprica says, I think it sounds like the controller, and if it dies, the car might just turn off, right? I don't want my wife driving my 2 kids around in a car like that.

MikePalm

It snowed last night so I tried to drive down a big hill here.

ABS doesn't work now either! No warning lights come on except when the car is sliding, then the one light flashes that says the car is slipping. Not fun to go down our very steep hill without regen brakes or abs. Wheels locked and started to slide very easily even with winter tires. Parked it and took my MDX down with no problems.

smassey321

It sounds like you are in fail safe braking mode which just uses pedal hydraulics. Since ABS is not working either, it is like the electronics does not know you are hitting the brakes (which would explain no codes). If the dealer were to attempt to bleed your brakes, they would hook up their system, press the pedal and the abs pump would run. Could be another clue.

MikePalm

Lexus told me today that "its an old car" and "its good enough to just have the regular friction brakes for now". And that they would have to check out if the abs really isn't working. He almost told me that since there are no warning lights that nothing is really wrong with the car and nothing they can do for me. And of course there was nobody higher up than him that I could talk to about it.

They can get me in on the 25th (18 days from now) but they don't know how to fix it, and they don't have a car for me to borrow until they can fix it.

What about the amazing Lexus customer service that I keep hearing about??

MikePalm

Lexus' Final Answer..... They don't know what is wrong and they are not able to diagnose it other than it is either a hybrid component or computer related problem since they ruled out all other mechanical parts.

"Sorry, its just an old car. There aren't any fault codes so nothing is wrong. The hydraulic braking system is working 100% so there is nothing to worry about."

Extended hybrid warranty doesn't cover me since I bought it with more than 150,000 km.

Pretty dissapointed with Lexus Sweden/Europe that they are unwilling to help.

salimshah

I generally do not peruse this forum and know very little about Lexus of Sweden/Europe.

If it was here in USAm this is what I would suggest doing,
Set a time to visit in person the Service manager. From the onset, tell him that the discussion is to find the root cause of the problem and not discuss who will pay for repairs. Get his attention that the behavior is abnormal. Remember expecting local mechanics or any mechanic to find root cause of every problem is asking for a miracle. The whole purpose of the visit is to get the service manager to be motivated to get to the root of the problem and lower your expectations that the mechanics may not be able to solve your problems. Use tact as you dont want the service manager to feel his shop is incompetent. Keep in mind you are dealing with mechanics and they have an ego, but they are also intrigued by hard problems to solve. So serve it as a challenge.

Next figure out where and when specialist on braking and regen will be making his rounds. There are Certified mechanics and then factory trained expert that makes a round. It may mean a trip for you as the mechanic may not be scheduled to visit Sweden.

Now on the technical side ... with intricate systems, there are not only backups but many factors influence how the system works. An expert knows how to disable certain systems to narrow down to the root cause.

Salim

kye04

Same problem here with a 2008 Highlander.... Please tell me if you found a fix...