Do not initially be concerned with the TRAC (Traction Control) and VSC (vehicle Stability Control) light having come on at the same time.
There is a 16 pin diagnostic socket under the driver's side of the dashboard. A scan tool is required to communicate with the computer in your car. The scan tool communicates with your car's computer and holds valuable information regarding the fault in your car.
Any reputable automotive repair shop should have the tool necessary to diagnose the fault.
Frequently the problem that has caused the Check Engine Light to come on in the first place on a Lexus is related to the other circuits (TRAC and VSC), fixing the Check Engine problem will fix the problem in all three systems