2021 Toyota Sienna Hybrid

brake sleeps sometime when i press brake pedal i took car to dealer once,they said need time i did not have much time took another time, they reseted system still... my warranty is over now. rear seat,make shake noise and check rear seat sign on dealer can't find problem. did not do anything since new car. i do not know any other 2021 sienna drivers have same problem.

FAILURE: Brake control system. Vehicle intermittently surges forward while braking at low speed, most often through a curve — the brakes momentarily release and the vehicle lurches before braking resumes. Appears to occur during the transition between regenerative and friction braking. Vehicle available for inspection. SAFETY RISK: Unpredictable momentary loss of braking at low speed, in parking lots, residential streets and curves where pedestrians and other vehicles are close. Driver cannot anticipate it. WARNING LAMPS: None. No lamp, no message, no stored trouble code. Present since early in ownership; purchased new September 2021. CONFIRMED BY DEALER: No. Reported to a Toyota dealer in 2022 under warranty. Dealer test drove, could not reproduce the intermittent condition, took no action. Also reported in writing to Toyota in August 2022; no substantive response. MANUFACTURER REMEDY: In May 2024 Toyota issued TSB T-SB-0047-24, a brake control module software update for this exact low-speed braking condition on 2021-2022 Sienna Hybrids. Warranty had lapsed, so it was applied at owner expense in late June 2026 at ~156,000 miles. The defect persists after Toyota's own remedy. The surge still occurs, including within the past week at ~157,000 miles. REQUEST: A TSB is not a recall — owners are not notified, and the software remedy did not eliminate the defect on this vehicle. Request that ODI evaluate whether this condition warrants a defect investigation and recall.

My 2021 Toyota Sienna Hybrid has an intermittent and dangerous brake failure where the brakes suddenly release pressure during normal braking. When slowing down—especially at lower speeds or approaching a stop—the brake pedal briefly loses resistance and the vehicle surges forward as if the brakes let go. I must immediately re‑apply hard pedal pressure to avoid rolling into traffic or another vehicle. The vehicle as a result can stop up to six feet past the intended stopping point in some instances. This issue is unpredictable and has occurred multiple times. It creates a serious safety risk. Toyota performed T‑SB‑0047‑24 (Brake ECU Reprogramming) on my vehicle, whereafter the brakes seemed to function normally for several months, but the problem resurfaced and occurred threee time in one week in May of 2026, which prompted me to bring it backk to Toyota for another look. The dealer has been unable to reproduce the issue and therefore has not repaired it. The veicle has been returned to me, and continues to have the problem intermittently at a random frequency. Toyota corporate Brand Engagement Center has been notified, and a case was opened (Ref # 260528002416). This case was closed however after telling me that the dealership connot reproduce the problem, therefore they cannot repair it. This appears to be a brake control defect involving the hybrid brake‑by‑wire system. Because the failure is intermittent and leaves no diagnostic codes, it is extremely difficult for the dealer to diagnose, but the safety risk is severe. I'd like to advise that I have owned and driven earlier hybrid models (2012-14) that never exhibited this type of brake failure. I'd also like to point out... an internet search of this problem reveals that this problem seems to be prevelant in newer Toyota hybrid models. This was confirmed by the service manager at my local dealership. I have not been informed of any continuing engineering efforts given the failure of the TSB.