NHTSA Complaint #11628419 — 2002 TOYOTA TUNDRA

My original owner 2002 Toyota Tundra Truck was being backed up in reverse with a utility trailer attached up a very, very moderate incline on a driveway pushing the trailer onto a gravel pad ALONGSIDE (parallel) the driveway. As it started to spin gravel the truck was put into a 4 wheel Drive LOW RANGE. This is in keeping with the TOYOTA owners manual publication 0M34417U Part Number 01999-34417 Print date 02-0109-01. We followed the manual instruction on 4 WD operation. Within a few feet the truck stopped as if the wheels had hit a curb and there was no further movement no matter the accelerator pedal position and the engine speed was unchanged as if it was in a stall. All of a sudden there was a loud bang underneath the truck and the truck raced rearward 8-10 feet jackknifing the trailer into a tree and upending the truck and trailer. We contacted Toyota on the incident and they had a third party look at the truck for brake condition, floor mat placement and throttle freedom at the body shop & Toyota closed the complaint file. Toyota IGNORED the circumstances and description of the incident in closing the complaint. We have been a very long time TOYOTA truck family and have owned SIX Toyota 4 wheel drives plus a Lexus all-wheel drive. In doing our own evaluation and investigation we have found that the truck went into a 4-wheel drive "wind-up" or "bind" and found information related on it from ASE Certification sites. NO MENTION of this potential issue is provided in the owners manual! We found that the torque from this can be over 4,000 ft/lb. and possible magnified even more by low range. When this bind suddenly is released the movement can be violent as happened here. Why is this not talked about in the owner manual? Why does Toyota ignore this reality? Indeed, the Toyota Rep. Mr. Ronald Inton said "he never heard of anyone backing up in 4 Wheel Drive"! WHAT?? We have the vehicle, photos, Toyota denial all available for review,.