The contact owns a 2006 Toyota Tundra. The contact stated upon taking the vehicle to an independent mechanic for a routine brake line repair, the contact was informed that the sub frame was severely corroded. The mechanic informed the contact that the frame could collapse if the contact continued driving the vehicle. Additionally, the contact stated that while driving at an undisclosed speed and depressing the brake pedal, the vehicle hesitated to respond. There was no warning light illuminated. The vehicle was not repaired. No further information was available. The manufacturer was made aware of the failure and referred the contact to the NHSTA Hotline for assistance. The failure mileage was approximately 35,000.