As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 253 BOS-DFW, CREW DECLARED EMERGENCY AND DIVERTED TO IAD DUE TO AFT AVIONICS RACK SMOKE INDICATION CAME IN FLIGHT. (AVIONIC SMOKE DET SYS-AFT AVIONICS CARGO RACK (LTV) )FOUND AFT RACK COOLING FAN ASSY SEIZED & TERMINAL LUG ON T1 WIRE 9842 OVERHEATED. REMOVED AND REPLACED COOLING FAN ASSY. RE-TERMINATED T1 TERMINAL ON WIRE 9842. OPS CHECKS GOOD. ALL WORK WAS IAW AMM 26-15-01 & 23-39-00. WD 23-39-00 DWG 99FS933302.