Owners of 2008 Toyota Highlander and 2008-09 Sienna models with automatic transmissions and AWD systems may complain of a transmission fluid leak from underneath the vehicle.
According to Toyota Motor Sales USA Inc., the leak usually appears at the vent at the top/front portion of the transfer case or at the joint where the transfer case bolts to the transmission.
A defective O-ring seal in the transfer case is the root cause of the fluid leakage. Installing an upgraded O-ring should eliminate further trouble. Note that the part number of the new, upgraded seal is identical to the old.
"Factory Fixes" is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected].