The vehicle is registered to me; my mother was the driver at the time of the failure. At ~2,963 miles, the truck developed intermittent check engine and ABS warning lights. The dealer pulled DTC C058A (brake system control module) and P25A2. Per GM bulletin PIT6012A, the battery was replaced and a brake plunger motor sensor learn was performed. The same codes returned within weeks. The dealer then diagnosed internal failure of the brake master cylinder and reservoir, documented the vehicle as "unsafe to drive," and replaced both under warranty. The truck sat at the dealer over six weeks due to a nationwide parts backorder. Repairs were completed April 4, 2025. On May 2, 2025, at ~6,500 miles, the driver was traveling downhill on a city street in the rain at roughly 20 mph. The brake pedal suddenly became hard and resistant. Despite full-force pedal pressure, the vehicle could not be stopped. It entered an intersection, struck another vehicle, then struck a tree. Front and side airbags deployed; the vehicle was totaled. The driver sustained a concussion, broken finger, and severe back and knee injuries, was transported by ambulance, and required months of concussion treatment including vestibular therapy. The hard, resistant pedal is consistent with failure of the electronic brake boost assist (eBoost) system, leaving only unassisted hydraulic braking (roughly 4â5x normal pedal force). This matches other owner reports and the class action in Barron et al. v. GM LLC, which ci