As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEICE PRESSURE CAUTION ILLUMINATED ON DESCENT WHEN BOOTS SELECTED TO SLOW. IAW THE CHECKLIST, SET MODE SELECT TO MANUAL AND THEN BACK TO SLOW. THE LIGHT EXTINGUISHED BUT THEN CAME BACK ON. THE MOST OTBD BOOT LIGHT ON LT WING DID NOT ILLUMINATE. DIVERTED AND ACCOMPLISHED UNEVENTFUL LANDING. PERFORMED FUNCTIONAL TEST OF AIRFRAME PNEUMATIC DEICING SYS IAW AMM TASK 30-11-00-720-801. OPS TEST GOOD. DEICE PRESSURE CAUTION DID NOT RETURN. NO FAULTS IN CDS. RETURNED TO SERVICE.