Unexpected vehicle acceleration - lack of adequate braking during disengagement of hybrid regenerative braking.

- Logansport, IN, USA

I have experienced the exact braking problem in my 2006 Lexus Rx400H as described in recent "car guys" column. While coasting to a stop with foot lightly on brake pedal, if I suddenly step harder on brake, it seems to disengage for a second before the brake takes hold again. My guess, same as the car guys, is that there is a slight delay in switching from regenerative braking to regular friction braking. It is disconcerting, but something I can live with as I am a cautious driver -- leave plenty of following distance, etc. This has happened occasionally, at various times, so "incident date" is fictitious just to get through this form.

- Golden, CO, USA

The contact owns a 2006 Lexus Rx400H. The contact stated when driving at speeds of at least 40 mph on a bumpy road surface, the braking system becomes faulty causing unpredictable stopping distances. The contact took the vehicle to a dealer to have a diagnostic test performed and the dealer was unable to duplicate the failure. The contact was concerned that the vehicle could potentially cause a crash due to the faulty brakes. There were no repairs made to the vehicle. The failure mileage was 52,000.

- Milwaukee, WI, USA

Momentary acceleration during normal braking. Problem occurs regularly (but not every time) during normal braking. Lexus dealer service writer reports this as normal and expected performance. It appears that normal braking starts with regenerative brakes and then transitions to friction brakes. There is a moment during the transition that braking power is lost and vehicle unexpectedly accelerates. To maintain even deceleration during every braking maneuver the driver must be particularly aware of this potential problem and be prepared to quickly apply significant additional pressure to the brake pedal during the transition phase then immediately remove the added pressure to prevent over-braking..

- Denver, CO, USA

I have a 2006, Lexus, rx 400 H. a Lexus certified used vehicle. The vehicle was new to me last summer. It accelerates slightly when I initiate braking 2 or 3 times out of 20 times. I thought it was "normal" for a car with regenerative braking. It startles you when it happens but hard pressure on the brake stops the car. You have to pay atttention each time you brake. What is scary is it accelerates a lot in about 1 of 100 times when I brake. At first I thought I was hitting both the gas and the accelerator... but I am sure I am not. The car will accelerate two car lengths before you can brake it. I thought it was dangerous and brought it to the dealer last year. We went for a test drive and the problem did not occur. The dealership recorded the complaint and told me to keep an eye on it. The 2 car length acceleration problem was worse in the hot months and it did not seem to occur in the winter months. The slight acceleration problem has not changed in frequency. With all this Toyota brake stuff, I wonder why I have not heard of this problem in Lexus hybrid cars too?

- Eagleville, PA, USA

Lexus Rx400H, accelerated while brakes were applied causing an accident. Also the vehicle's brakes were such that the there was a slight delay that had to compensated for or you would pass intersections or turns. The vehicle still accelerates at times when brakes are applied.

- Kenosha, WI, USA

S10 appropriate handling re Toyota recall for prius brake issue, owner of a 2006 Lexus 400H concerned with braking problem experience w/vehicle. The consumer stated the vehicle would continue to accelerate when the brakes were applied. The incident would occur when driving at higher speeds and then slowing down to stop.

- Danville, CA, USA

I was approaching a light intersection at 50mph. When light changed to red I tried to apply brakes about 1,000ft from intersection. Car did not slow down and brakes appeared not to be working. I veered into median to avoid stopped traffic in front of me and then entered intersection clipping the back of another vehicle. Lexus dealer reported no defect with brakes. This vehicle had been stored in a Florida garage and it was the 1st time it had been driven in several months. This has not happened again to this vehicle to my knowledge.

- Cape Coral, FL, USA

Re: Lexus Rx400H not on any recall list by Toyota. Have had multiple incidents of braking/acceleration problems. Toyota won't do anything except say bring it in for a test drive. It has already been test driven several times and the problem does not duplicate. It is rare, but it is dangerous. Toyota just shrugs it off. I know what the car does, I've driven it for nearly 3 yrs with approx. 12 incidents of the problem. Can you help?

- Lake Elsinore, CA, USA

When braking, if a pothole or bump in the road is hit or when either the temperatures are really cold (on occasion) or the hybrid battery charge is close to full, the car's regenerative braking stops and there is a delay in the friction brakes being applied by the system. When this occurs, the car seemingly jerk forward for a second. Dealer stated that there is nothing wrong with the brakes. This behavior has recurred over the last 4 years/60,000 miles. No fix from Lexus. Had to learn to expect this behavior and drive accordingly (on occasion having to emergency brake with ABS activated).

- Alpharetta, GA, USA

Lexus Rx400H has a brake issue. Instead of stopping it sometime accelerates and continuous braking leads it to stop. The hybrid technology forces many of us to change all four company fitted all four tires just in 2 years. Very disappointed by paying premium for premium brand but not getting premium quality!

- Bloomington, IL, USA

Ever since I purchased the car in late 2005, my 2006 Lexus rx 400H hybrid SUV will lose braking effort when going over a bump. I have press harder on the brake pedal to maintain braking force to stop the car when this happens. This happens every time you go over a certain type of bump when the brakes are being applied. There is no light or warning sound associated with the loss of braking effort. If it possible to safely remove your foot from the brake pedal or a second, and then re-apply the brakes, the brakes are restored to normal operation. Vigilance is required in increasing brake pedal pressure when this happens to avoid a crash. I have to complained to several Lexus dealers and to Lexus central customer service about this issue. I was told the company never received any complaints about the problem and/or was never able to reproduce the problem in my car.

- Haymarket, VA, USA

I own a 2006 Lexus rx-400H, and I have experienced braking problems while driving this vehicle for the past 1-2 years that has become progressively worse. The problem generally occurs at speeds between about 25-45 mph, and involves a sudden decrease in braking deceleration with constant brake pressure, making it necessary to quickly apply more pressure to bring the car to a stop. From my own observations, as well as from technicians at the dealership, this problem appears to be related to the hybrid regenerative braking system, which seems to abruptly stop regenerative braking without compensating with additional friction braking. After finally having this phenomenon confirmed by the dealership after over well over a year of experiencing it, I am being told by the dealership that Lexus engineers are calling this "normal" and "expected" behavior of the car. I am filing this complaint because I feel that, while it may be "normal" or "expected" to Lexus, it presents a serious a danger to myself and other drivers when the vehicle does not respond to braking in a predictable manner. I have on several occasions been startled by occurrences of this problem when approaching a stop sign or cross walk, and consider myself fortunate that I've been able to react in time to avoid hitting the vehicle in front of me, or a pedestrian. This problem has become severe enough that it can be fairly easily reproduced in the first few minutes of test driving.

- Draper, UT, USA

I have 2006 Lexus rx 400H and have the same problem with my brake as prius has. When I slow down a car and my car hits a rough patch of surface, or pothole, the brake seems to release and I experience 'brake surging'. several instance I almost hit a pedestrian because the car surged forward at an intersection. I brought the issue to the Lexus dealer but they said they could not replicate the problem during their examination. Help!

- Chicago, IL, USA

I have a 2006rx 400H, with 60K miles, and an extended warranty. I broke down 2 weeks ago on a 2 lane highway, without brakes, loud warning sounds, and failure lights all over the dash. My choices at that time were to stop in the middle of the road, center divider did not exist but instead was a concrete barrier, and right hand shoulder eased off to the river. Since it was not commute time, traffic was light and I was able to slow down and pull off at the old mare island base in vallejo. My car was towed to freeman Lexus, santa rosa, where I bought my car and have had all servicing done. I was informed that the computer needed to be replaced and would take a week or so to get. The job was done on wed. Feb 11. I went to the dealership to pick it up and was on my way to sf to teach a class, when less than 30 miles from the dealership, on highway 101, in the middle of commute traffic, failure alarms and lights sounded and brakes did not work. I was shocked and tried to quickly get my car over to the slow/right hand lane and tried to slow down. I finally, 2 miles later, found an exit ramp and brought the car to a stop after a long approach to the ramp. I was stopped between the lane and the shoulder. Called the dealer again to let them know of the failure. They now have the car towed back at freeman Lexus. If this computer was replaced, how could this failure happen again. Additionally, I had to reach out to all my students to cancel the class at the last minute. This is a catastrophic failure and both times could have ended in injury, serious collision, to others or myself. While I have always been delighted with this vehicle and Lexus products and service, I do not know what I could be told regarding the repair of this car, that would make me feel safe. I feel like with these 2 failures, two potentially serious situations were averted. How can I be sure that this won't happen again with terrible or deadly consequences?

- Vallejo, CA, USA

Vehicle was normally maintained and lightly driven. One year of age of the vehicle, when driven on level dry surfaces, the braking of the vehicle became erratic and remains erratic. In everyday use the vehicle will tend to overbrake or underbrake depending upon the mechanical loading of the hybrid drive. The onboard firmware is not properly accounting for integrating the stopping power of the brakes and the hybrid drive. This causes driver confusion and in some cases hazardous failure to brake conditions when the hybrid drive unexpectedly and erratically ceases it's contribution to the braking force of the vehicle. I.e. if the driver does not immediately compensate, the vehicle will lunge forward at low speed and within a few feet of pedestrians and other stopped vehicles in traffic. The dealership states that nothing can be done and that erratic/loss of braking is normal for this model. There are no recalls or sbs posted to upgrade the firmware, braking/hybrid drive systems. Lexus Rx400H, 2006 model.

- Annandale, VA, USA