TL*THE CONTACT OWNS A 2005 CADILLAC STS. WHILE DRIVING 15 MPH, THE SYBILLA TRACK LIGHT ILLUMINATED AND THE REAR OF THE VEHICLE BEGAN SLIDING TO THE LEFT. THE CONTACT DEPRESSED THE BRAKE PEDAL AND THE LIGHT ILLUMINATED AGAIN. THE VEHICLE STRUCK THE GUARDRAIL AND CAUSED $7,014.75 WORTH OF DAMAGE. THE CONTACT WAS INJURED. THE ABS DID NOT MALFUNCTION AT ALL. ONSTAR STATED THAT THE YAW RATE SENSOR MALFUNCTIONED. THE VEHICLE WAS TAKEN TO A BODY SHOP IN SPRINGFIELD, VA. THE PURCHASE DATE WAS UNKNOWN. THE CURRENT AND FAILURE MILEAGES WERE 50,880.