As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA FLIGHT NR 2396: PITOT HEAT STANDBY CAUTION ILLUMINATED HOLDING SHORT OF RUNWAY. STAYED ON ABOUT 15 MINUTES AND WENT OFF DURING TAXI BACK TO GATE AND THEN RE-ILLUMINATED AFTER ABOUT 45 SECONDS. MAINTENANCE: OHM CHECKED THE STANDBY PROBE. CHECKED SPLICES AT THE TMCU. CDS FAULTED THE TMCU. REMOVED AND REPLACED THE TMCU. OPS CHECKED GOOD IAW Q400 AMM 30-11-01-000-801 AND 30-11-01-400-801. OPS CHECK THE PITOT/STATIC SYSTEM ANTI-ICE. CHECKED GOOD IAW 30-30-00. AIRCRAFT RETURNED TO SERVICE.