One problem related to driveshaft has been reported for the 2012 Toyota Sienna. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2012 Toyota Sienna based on all problems reported for the 2012 Sienna.
Service tech at the Toyota dealer said my electromagnetic coupler / viscous coupler and driveshaft ujoint seized. After further research online it seems its common. Wondering if Toyota would put out a recall?.