One problem related to wiring has been reported for the 1999 Toyota Sienna. The most recently reported issues are listed below.
: the contact stated while driving 35 mph on a rainy day on flat road conditions, the vehicle lost all back lights. The rain water created a short circuit on the vehicle harness cables in the hitcher. The cable harness was required to connect the trailer lights. The contact disconnected the harness cables to restore the vehicle back lights. The manufacturer was contacted who referred the contact to a dealership.