One problem related to brake grinding noise has been reported for the 1998 Toyota Sienna. The most recently reported issues are listed below.
Front brakes with loud grinding noise especially bad when applied going downhill. Dealer says all the Toyotas do that! this is my third Toyota vehicle and have experienced the same problem with brakes on all three vehicles. Guess this will be my last Toyota! worried about brakes possibly failing as it "takes too long for braking to be effective". This has been a problem since aprx. 12,000 miles! brakes have been checked and are at 70% (30% worn). The rt. Side passenger sliding door is difficult to open from the inside, and when finally open, difficult to get it to lock in place (kids can't do it) I have to slam it back really hard to get it to lock in open position to avoid slamming shut on us! it also rattles while driving. The electrical system intermittenly stops working correctly, driver unable to control passenger-side windows and locks. Even unable to unlock driver side on one occasion.