Since you asked nicely, it refers to the traction control unit. Usually throwing an error code when it thinks theres a problem. Mine did that for about 2 months and I ignored it and it went away. Try this, drive around with the trac off for a few days, so everytime you start the car up turn the trac off. This may refresh previous codes and act as a new install if the unit doesn't run for a while when the cars in normal operation. Actually, does the Trac light automatically come on when you start the car up and before its put into gear?