As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER DE-ICE WE TURNED THE PACKS ON AND VISIBLE SMOKE IN THE COCKPIT FOLLOWED BY A MAIN CARGO FIRE INDICATOR. SMOKE CLEARED AND MAIN CARGO LIGHT WENT OUT. PERMORMED FIM 21-00 TASK 806 RAN BOTH ENGINES NO DEFECTS NOTED NO SMOKE OR FUMES PRESENT. SUSPECTED REASON APU OR PACKS INLETS INGESTED GLYCOL DURING DEICING OF AIRCRAFT.