— Toyota is recalling about 310,000 model year 2005-2007 and 2009-2010 Sienna minivans in the U.S. to fix problems that can cause the minivans to unintentionally roll away.
The Sienna is equipped with a shift lever assembly that contains a shift interlock system which uses a shift lock solenoid that includes a slider and a stopper. Those parts are used to prevent the shift lever from moving out of the PARK position unless the ignition is on and the brake pedal is pushed down.
Toyota says it's possible grease was applied improperly to the shift lever assembly, grease that could transfer to the slider and stopper and deteriorate over time. This can cause the slider and stopper to move together, allowing the shift lever to be moved out of the PARK position without pressing on the brake pedal.
Toyota received a report from Canada about a shift lever that moved out of PARK, causing engineers to inspect if the shift interlock system functioned properly. The shift lever could not be moved out of the PARK position unless the ignition was on and the brake pedal was pressed. There were no problems found in any components related to the shift function when the minivan was inspected.
Investigators collected the shift lever assembly and later found that while the shift interlock functioned properly under the normal shift operation, the stopper could move in sync with the slider if the shift lever was deliberately operated very slowly.
Further investigation found that grease applied to the shift lever had transferred to the solenoid and the grease contained metal debris and scratch marks on the surface of the stopper and slider. Because the movement did not occur when the metal debris was removed, Toyota believed this was an isolated case caused by the foreign material.
Toyota then received three reports from the U.S. indicating a similar problem as reported in Canada. The Sienna shift lever assembly installed in one of the three minivans was recovered and investigated and no defects or burrs were found, however, the tip of the stopper had been damaged.
It was theorized that excessive force was applied to the shift lever, causing the stopper to be damaged and allowing the shift lever to be moved out of the PARK position. After that, Toyota received four more reports but because no trend was found among these cases, Toyota continued to monitor the field.
In 2017, Toyota received a customer complaint in May from the U.S. and was able to inspect another minivan in July. Both vehicles and shift lever assemblies were inspected but no abnormalities were found in the shift interlock function of the first Sienna.
But during the July inspection, the shift lever could be moved out of PARK without the brake pedal pressed by using a deliberate, slow motion with force.
Lubricating grease and dirt were seen on the solenoid and on the sliding surface of the stopper and slider of both assemblies. The shift lever assemblies of these Siennas were recovered and investigated. In one of the two solenoids, Toyota says that damage, which may have been caused by excessive force, was seen on the tip of the stopper.
In addition, the recovered shift levers could not be moved out of the PARK position under normal shifting operations. However, in both assemblies, the stoppers could occasionally move downward together with the slider under deliberately slow-shift operations.
Nineteen shift lever assemblies were recovered and investigated from in-use minivans. Engineers confirmed that none of the shift levers moved out of the PARK position under normal shift operation. However, the stoppers in nine of them moved partially in sync with movement of the slider if moved under deliberate slow shifting operations.
The automaker determined the impact that deteriorated grease was having on the problem when engineers used new grease on the solenoids and learned the problems disappeared, causing Toyota to decide on a recall.
Toyota dealers will replace the shift lock solenoid and reapply the correct amount of grease once the recall begins on December 1, 2017.
Owners may contact Toyota at 800-331-4331. Toyota's number for this recall is H0V.