As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE POWER IS OFF AND GROUND SVC BUS IS ON WITH GPU CONNECTED EMERGENCY LIGHT TURN ON WITH EMERGENCY LIGHTS SWITCH IN THE OFF POSITION. REMOVED FROM SERVICE. COULD NOT DUPLICATE. EMERGENCY OP CHECKS GOOD. REF AMM 33-50-00-710-801-A. RETURNED TO SERVICE.