One problem related to wiring has been reported for the 2008 Toyota Sienna. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Toyota Sienna based on all problems reported for the 2008 Sienna.
I had trouble accelerating up a hill and stalling and turning off on the road. I took my vehicle to my Toyota dealership for inspection and was told that rodents or such type had chewed on the electrical wiring harness because of the insulation materials attractiveness. After been first offended, I then remembered seeing a squirrel near the vehicle I presumed innocently taking shade from the hot florida sun. During that time I parked my vehicle in my driveway outside. I advised the dealership of this and they confirmed that indeed such animal would liking have chewed on the harness wiring causing the issue at hand. I paid out of pocket for this repair since I was told it was not under warranty. It has come to my attention that the Toyota dealership was aware of this type of animal and the attraction to the soy based insulation around the electrical wiring harness. There now are two class action cases regarding this matter with Toyota.