Toyota Motor Corp. said Wednesday it is recalling 878,000 vehicles because some drivers say the rear suspension has failed, causing them to lose control.
The recall includes 760,000 2006-2011 RAV4 SUVs and 18,000 2010 Lexus HS 250h cars in the U.S., and comes less than two months after the government opened an investigation into reports of failures in rear tie rods.
An additional 100,000 vehicles, including 99,000 RAV4s, are being recalled in Canada.
Four drivers reported they lost control while driving at high speeds.
Toyota says nine crashes and three minor injuries resulted from the problem.
The Japanese automaker told the National Highway Traffic Safety Administration that the problem is not a manufacturing defect, but rather the result of improper tightening of turnbuckle nuts by service technicians.
Toyota said that if the nuts on the rear suspension arm are not tightened properly during a rear wheel alignment, excessive movement may occur at the threaded portion of the arm, followed by rust.
The automaker said it first began receiving reports of the condition in 2008, but didn't detect a "clear trend of failure" and said the failure rate was low. In August 2010, Toyota introduced a new suspension arm on the vehicles.
In August 2011, it inspected 52 vehicles and found that just one, with a history of rear wheel alignments, had loose nuts.
In May, Toyota received a complaint of a customer crash. The automaker inspected the scene of the crash and learned that non-factory applied lubricant had been used, evidence of rear wheel service. The company inspected 25 vehicles in service and found loose nuts on one vehicle.
NHTSA opened its investigation in June.
"Toyota has concluded that this issue is caused by the improper tightening of the lock nut during adjustment of the rear wheel alignment in the field," Toyota told NHTSA.
"However, Toyota decided to conduct a voluntarily safety recall campaign to ensure proper tightening of the lock nuts."
Toyota is developing a fix. Once the remedy is available, the automaker will notify vehicle owners.