NHTSA Complaint #10473654 — 2006 TOYOTA PRIUS

WHILE MY 16 YEAR OLD SON WAS PRACTICING DRIVING MANEUVERABILITY WITH MY WIFE IN A PARKING LOT, THE STEERING SHAFT COMPLETELY FAILED AND THE VEHICLE COULD NOT BE CONTROLLED OR STEERED. THEY PARKED THE CAR SAFELY AND GOT A RIDE HOME. IT WAS FOUND THAT THE SPLINES ON ONE OF THE INTERMEDIATE STEERING SHAFTS COMPLETELY FAILED. THE UPPER PARTS OF THE STEERING MECHANISM COULD TURN WITHOUT TURNING THE LOWER PARTS. TOYOTA HAD A RECALL ON SOME 2004-2006 VEHICLES WITH THIS EXACT DESCRIPTION OF PARTS BUT MY VIN IS NOT INCLUDED IN THE RECALL. MY FAILURE IS EXACTLY AS DESCRIBED: LOW SPEED WITH THE STEERING TURNED AT THE END OF TRAVEL. SEARCHING THE PRIUS FORUMS ON LINE, THIS IS A COMMON PROBLEM. EVEN CARS THAT HAVE HAD THEIR STEERING MECHANISMS REPLACED HAVE FAILED A SECOND TIME. THE ISSUE IS A DEFECTIVE DESIGN OF THE STEERING SHAFT. FIRST, THE ELECTRIC POWER STEERING PLACES FORCES ON THE STEERING SHAFT THAT WOULD NOT EXIST IN HYDRAULIC POWER STEERING. THE SPLINE NOW HAS THE FORCE OF THE DRIVER PLUS THE BOOST OF THE POWER STEERING. AT THE END OF TRAVEL, THE POWER STEERING IS FORCING THE LINKAGE TO TURN EVEN THOUGH THE DRIVER IS JUST SLIGHTLY TURNING THE WHEEL. THE RACK AND PINION AND THE ASSOCIATED SHAFT AND LINK WERE DESIGNED FOR NON BOOSTED FORCES. THE SECOND DESIGN DEFECT IS THE FACT THAT THIS SAFETY CRITICAL PART DOESN'T INCLUDE SOME TYPE OF REDUNDANCY FOR FAILED SPLINES. IN STATE OF THE ART DESIGNS AVAILABLE SINCE THE 1970S, THE CLAMPING BOLT PROVIDES A SECONDARY FAIL- SAFE FOR LOOSING THE SPLINE INTERFACE. IF THE SPLINES FAIL, THE BOLT INTERFERES WITH THE SHAFT AFTER A FEW DEGREES OF MOVEMENT. THIS GIVES THE DRIVER A SLOPPY BUT SAFE WAY TO DRIVE THE VEHICLE. UNLIKE THE PRIUS FAILURE, THIS SYSTEM CAN KEEP THE DRIVER IN CONTROL. MY TOYOTA DEALER DID NOTHING FOR ME BECAUSE THE VEHICLE IS OUTSIDE OF THE WARRANTY. TOYOTA CUSTOMER LINE DID NOTHING. *TR..UPDATED 06/28/13 *BF UPDATED 07/1/2013 *JS