What was found
IAD/PWM - FLT 6578 - DURING TAXI OUT AT 1800 HRS ON 7-16-97, EXPERIENCED A RT IEC CAPTION LIGHT ILLUMINATION PRIOR TO TAKEOFF. CREW AND THE AIRCRAFT RETURNED TO THE GATE WHERE MAINTENANCE CONTROL WAS NOTIFIED OF THE DISCREPANCY AND THE MAINTENANCE PERSONNEL WERE DISPATCHED TO THE AIRCRAFT FOR TROUBLESHOOTING. IT WAS DISCOVERED THE LEAD TO THE T-2 SENSOR HAD FRAYED AND WAS SHORTING OUT. MAINTENANCE REPAIRED THE LEAD AND FUNCTIONALLY CHECKED THE SYSTEM IAW THE MM PROCEDURES. AIRCRAFT WAS THEN RELEASED FOR SERVICE. (X)