I have a 2002 Toyota Sequoia. The VSC Trac light comes on occasionally and will usually (but not always) go off if I turn off the engine then restart. This started soon after my OD light started coming on. It also will sometimes go off if I restart the engine. The overdrive is sometimes actually on and sometimes not on when the light comes on.
Today (5/2/12) the check engine light came on and the technician said that the computer indicates only 1 problem...... the brake booster switch.
After reading some of the experiences of other Sequoia owners I am a bit frightened! I have had no driving issues over the several months that this has been going on, including a 1600+ mile trip, so far, but would love to define the actual problem and fix it.