As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT THE COMPLETION OF THE BEFORE TAKEOFF CHECKLIST, DURING MASTER RECALL, BOTH PACK LIGHTS ILLUMINATED. LIGHTS EXTINGUISH WITH MASTER CAUTION RESET. GROUNDED - YES. ACCOMPLISHED PACK/ZONE TEMP CONTROLLER BITE REF B737-900 AMM 21-61-00, #1 CONTROLLER LOGGED EXIT SRADA, #2 CONTROLLER LOGGED INLET & EXIT SRADA. RETEST AND CLEAR OK WITH NO FURTHER FAULTS.