NHTSA complaint #11754929

Owner complaint summary

2023 Toyota Highlander Hybrid Regenerative Brake Transition loss of brake pad pressure resulting in acceleration of the vehicle under downhill conditions. Have momentarily experienced the loss of braking frequently during braking when going downhill. This results in the vehicle gaining speed during this 1 or 2 second period before braking returns. In one case it allowed our car to get dangerously close to the vehicle ahead of us but fortunately I was able to push the brakes harder to prevent an accident but did require aggressive braking. Luckily no one was behind us which may have resulted in the person following us braking hard or possible hitting us. This was a known issue for previous year Toyota Highlander models and Toyota issued service bulletin T-SB-0059-23 which is stated to only be for model years 2020 - 2022. So, Toyota dealers say they do not have a fix that applies to the 2023 model. It has been indicated that the dealer is unaware if any action is being taken by Toyota to address this issue in the 2023 and later models. We have multiple people driving this vehicle and this sudden loss of braking power is very concerning. The loss of braking force occurs upon the transition from regenerative braking to standard hydraulic breaking. Below are words from the Toyota Technical Service notice concerning the problem. "Highlander Hybrid vehicles may be sensitive to the momentary transition from regenerative braking to hydraulic braking under certain driving conditions, such as while driving downhill, or turning with light brake pedal application. The brake actuator control module can be updated to improve brake feeling for this condition. Follow the Repair Procedure in this bulletin to address this condition."