One problem related to roof and pillar has been reported for the 2004 Toyota Sienna. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Toyota Sienna based on all problems reported for the 2004 Sienna.
On two separate incidents and in two separate car wash establishments, the sunroof on my 2004 Sienna just purchased in July '04 leaked. Incident #1 both my husband and I witnessed the back edge of the sunroof open up while going through the drying process and hence the h2o that was on top of the roof and glass traversed around the edges and into the car. Incident #2 I was not watching for a similar occurrence but I received a bath of water on top of my head, coat and lap. I examined the sunroof and it was wet on at least 3 sides (2 sides and back side). Upon leaving and then braking h2o came down around and through the openings surrounding the map lighting in between the two front seats. When I took the vehicle to the dealer they told me that my sunroof is operating normally and that a car wash is not a normal condition. I disagreed w/them. They subjected the vehicle to high pressure water but did not re-create the problem because they did not take the vehicle through a car wash. They were questioned on this. They're still contending that my car is fine. I say it is not, a sunroof on a 2004 vehicle w/less than 10k miles should not leak or open up. Investigating this would be appreciated.