As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TAIL DE-ICING WOULD NOT ACTIVATE WHEN SELECTED EN ROUTE. ALSO, AIRFOIL ICE PROTECTION PRESSURE ABNORMAL LIGHT WAS ILLUMINATED. FLIGHT RETURNED TO DTW AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED THE TAIL DE-ICE TIMER, OPERATIONAL CHECK NORMAL.