2024 Toyota BZ4X

The vehicle experienced a sudden, catastrophic brake-by-wire system failure while operating in one-pedal driving (Regeneration Boost mode). While decelerating at a low speed behind an 18-wheeler semi-truck, the vehicle failed to continue slowing down. I immediately depressed the physical brake pedal, but the vehicle completely ignored the foot pressure. The pedal and braking system became completely unresponsive, and the vehicle kept rolling forward uncommanded. Despite keeping the brake pedal fully depressed, the vehicle did not decelerate, resulting in a front-end low-speed collision with the metal rear bumper of the semi-truck. Because the collision occurred at a very low speed, the operator of the commercial truck was unaware of the impact and safely continued driving forward without stopping. The vehicle's brakes entirely refused to re-engage until I frantically pumped the physical brake pedal and cycled/pressed vehicle control power switches. This action seemingly forced the electronic braking modules to reboot or re-establish hydraulic pressure, allowing the vehicle to finally come to a stop. The vehicle was subsequently removed from the active roadway. This is a severe, life-threatening safety defect involving a total loss of electronic brake-by-wire and friction braking application without any mechanical override intervention, presenting an extreme hazard. The vehicle has been towed directly to an authorized Toyota dealership for a comprehensive electronic diagnostic pre-scan of the Skid Control ECU, Electronic Parking Brake system, and 12-volt auxiliary power systems to retrieve the stored DTC fault logs and freeze-frame data.

The vehicle experienced repeated electrical and brake system malfunctions that pose serious safety concerns. On multiple occasions, the brake pedal became stiff and unresponsive while driving, and the parking brake system failed to engage properly. In addition, the ignition system often failed to start, even when the battery and all power indicators appeared normal. At times, the vehicle’s electrical system completely shut down without warning — causing loss of power functions, dashboard lights, and essential safety controls. These failures occur intermittently and unpredictably, making the vehicle unreliable and unsafe to operate. The issue has been reported to the dealer for inspection, but the problem continues to occur. It appears to be related to the vehicle’s electronic brake control and ignition system. This malfunction places the driver and others at potential risk, especially if the brake system or electrical components fail while the vehicle is in motion.

2024 BZ4x, 590 miles on ODO. Purchased the car on Sunday, 03/23/2025. Monday Morning - Turning on the Car (In my garage). I had it in "ready" while I tried to connect my Toyota app to the car, While talking to Toyota engagement for help.. (Never was able to change the primary driver on it.) The accessory lights flickered and a bell went on and off. Then the car went totally black. Toyota called a tow truck driver. He jumped the 12 volt. It gave it enough juice so I put in reverse and there was a Loud Grinding noise. "Brake System Malfunction- Take to Dealer." Tow truck loaded it up, grinding and all, took it to Toyota. There, found out the 12 volt battery died. No reported grinding when off loading or at the dealer. Toyota Dealer replaced the 12 volt battery on Monday 03/24/2025. Picked it up, drove it around about 40 miles and parked it in my garage. Parked with >80% battery on Lith battery Monday night 21:00. Sat in the Garage on Tuesday. Wednesday Morning 08:00am, 12 Volt COMPLETLY DEAD. It's back at the dealership. MY safety concern - Does this mean the Brake system will "malfunction" if the 12 volt battery isn't holding enough charge to operate the BRAKE SYSTEM?! Not sure if it means the parking brake or the actual brakes.