As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 177 - DAY TO MDW - SMOKE EMANATED FROM AUXILIARY HEAT SWITCH. CREW PULLED CONTROL CIRCUIT BREAKER AND PERFORMED 'SMOKE IN COCKPIT OR CABIN CHECKLIST'. AIRCRAFT LANDED IN MDW UNEVENTFUL. MAINTENANCE INSPECTED SYSTEM AND FOUND THE CONTROL SWITCH INTERNALLY SHORTED. REPLACED SWITCH AND OPERATIONAL CHECK WAS SATISFACTORY. AIRCRAFT WAS RETURNED TO SERVICE.