On September 28, 2012, approximately 1215 eastern daylight time, a Learjet Inc 60, N862PA, departed the left side of the runway following an aborted takeoff from Teterboro Airport (TEB), Teterboro, New Jersey. The two certificated airline transport pilots on board were not injured, and the airplane was not damaged. Instrument meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the flight, which was destined for Lehigh Valley International Airport (ABE), Allentown, Pennsylvania. The positioning flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. The two pilots each provided written statements to a Federal Aviation Administration (FAA) inspector, and their accounts of the incident were similar. They reported that all pre-taxi and pre-takeoff checks were completed normally with no anomalies noted. After positioning the airplane on the runway for takeoff, the engine throttles were advanced to takeoff power. The pilots released the brakes, and shortly after beginning the takeoff roll, they received an aural warning and the nose gear steering disconnect light illuminated on the master caution panel. The airplane veered left, and the pilots aborted the takeoff while attempting to maintain directional control by rudder application and differential braking. The airplane's nose landing gear and left main landing gear exited the left side of the runway, where the airplane came to rest undamaged. During post-incident maintenance and troubleshooting, the airplane's nose wheel steering computer was replaced, and subsequent low- and high-speed taxi tests confirmed normal operation of the nose wheel steering. According to FAA and company records, the airplane was manufactured in 1993. Its most recent approved inspection program (AAIP) inspection was completed on March 1, 2012. The removed nose wheel steering computer was sent to the manufacturer's facility for further testing, where it performed within specifications. The unit’s history log contained 22 power supply out-of-tolerance conditions, indicative of repeated attempts to calibrate the unit. The recorded data ended with one “strut response incorrect” fault code, and one “strut inputs disagree” fault code, consistent with a failure of the strut servo at the time of the event. The failure, however, could not be replicated in post-incident tests, and no repairs were required to return the unit to service.