As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TAXI BACK FLT 8699 SEA: FLIGHT 8699 TAXIED OUT, ON RUN UP PILOT DISCOVERED THE DEICE BOOTS DID NOT INFLATE ALL 3 CYCLES IN AUTO MODE. AIRCRAFT TAXIED BACK TO RAMP FOR MAINTENANCE. MAINTENANCE REMOVED AND REPLACED THE DE-ICE TIMER. AIRCRAFT RETURNED TO SERVICE.