Not for certain, but accordomg to the local Goodyear store, who hooked it to the computer, it is the evap. system within the emissions system. The Toyota dealer has to fix it. The dealer I spoke to indicated that the "check engine" light coming on automatically triggers the "VSC Trac" light and the "VSC Off" light. Once the evap system problem is corrected, they will reset the system and it should take care of it. I have not yet taken it in to the dealer to have it fixed as they said it was not an urgent situation. I will probably get it in there this week.