As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CONT CAB ZONE TEMP LIGHT ILLUMINATED. LIGHT TURNS OFF AFTER MASTER CAUTION RESET. GROUNDED-YES. BITE CHECKED NR 2 ZTC. FAULTS CONT CABIN TRIM VALVE, REF B737-800 FIM 21-62 TASK 832. PERFORMED VERIFY TEST W/NO DEFECTS NOTED. FAULT RESETS. ETOPS GROUND VERIFICATION TEST SUCCESSFUL.