2024 TOYOTA Sienna

Looked online to see if other Sienna drivers had the same issue with the hybrid system. Brakes are accelerating a bit even when already pressing on the brakes. It has happened enough times to be concerning. We have not taken it to the dealearship as of yet but will be getting in touch soon , now that we know it's a known issue. No warnings from vehicle.

Dear Sir/Madam, I am writing to formally raise a complaint regarding a serious and ongoing issue with my 2024 Toyota Sienna XLE AWD, purchased in April 2024 in Illinois. From the very first day, the trunk door has not functioned properly — often failing to close, randomly opening, or requiring manual force to shut. Despite repeated service visits across multiple states (IL, SC, NC) and investing considerable time, fuel, and lost income as a contractor, this issue persisted for over 18 months, creating safety concerns and inconvenience for me and my family. Key Issues: Trunk door opens on its own – even while reversing, creating serious safety risks. Malfunctioning power close mechanism, requiring manual closure frequently. Unreliable performance: door would close, then immediately re-open. Visited Toyota service centers at least 6 times across 3 states. Each visit took 2–3 hours, costing me work hours as a contractor. Customer service experience has been poor, especially with manager Patte, who: Failed to schedule proper service appointments. Directed me without coordination. Refused to escalate my request or connect me to her manager. Dismissed my request for compensation by saying, “It’s your issue.” Please help me on this issue. Thanks in advance.

Keeps bottoming out suspension is specification is stated at 5.6 inches and I measured 3.3/4 unloaded never get a response on my complaints from my last repair and resolution on what they admitted that suspension was too low and wouldn’t put it in writing only saying that vantage mobility saying that it’s height requirements are as stated by vantage but no mention of ground clearance that I wanted them to verify that it’s specifications are stated at 6.5 inches and i measured 3 3/4 empty then they tell me not to go by specs and I’m a retired from wright Patterson Air Force base in the engineering department with logistics command and I’m like really guys you have to to have a specifications for a engineered system and they can’t even call back after they admit you have to go by specs! And then the authorized repair specialist tells me i had a bad brace on the front tire that was welded wrong and didn’t even mention it on the invoice or reported it to vantage mobility to call me about anything I had concerns about ?

On various occasions while braking there is a sudden acceleration that occurs. Generally lasting less than 5 seconds. More noticeable going down hills but has occurred on standard driving. Date provided is most recent occurrence after service from Marietta Toyota for recall and 25k service.

On rare occasions (about once every 500 miles), when uniformly applying force to the brake pedal, the deceleration suddenly ceases and the vehicle seems to jerk forward. To a passenger, it feels like the driver's foot slipped off the brake pedal, but the driver continued to provide the same uniform force to the brake pedal and lost all deceleration. Typically, the driver is startled and presses significantly harder on the brake pedal jerking all occupants forward. The brakes re-engage and continue the deceleration at a much higher rate. Toyota addressed this problem with TSB 4724 which involved reprogramming the brake actuator assembly. This corrected the problem for about 3 months, but it is now occurring again. When the car was taken to the Toyota dealer again, the technician stated that TSB 4724 was cancelled, he could not duplicate the action (even though he was told it only happened on rare occasions), and claimed that the "brakes function properly as they should." Fortunately these loss of braking incidents have only occurred on dry pavement so that the driver did not lose control of the car when slamming on the brakes to compensate for the loss of deceleration. Coming down a hill on a snow covered road could have caused the vehicle to slide into an oncoming lane. It is my speculation that there is a null spot that exists during certain circumstances which causes there to be a "gap" between when this hybrid vehicle transitions between the dynamic hybrid brake and the friction wheel brake. Both braking systems independently work fine, but the transition between them (on rare occasions) does not occur continuously. This causes the driver to experience an unexpected loss of braking which, under the right conditions, could cause the driver to loose control of the forward motion of the car. As an engineer, I feel it is unacceptable for a safety system (braking) to not properly operate 100% of the time! On a Toyota owner's site, others have seen the same.

Intermittent unexpected acceleration during braking. This has occurred while braking into a downhill as well as at low speeds when turning into a parking space. Additional braking is required to stop vehicle or maintain desired braking.