As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE AT FL 340, THE EMERGENCY LIGHTS IN THE CABIN (ALL OF THEM) ALONG WITH THE ASSOCIATED "EMER LTS ON" EICAS STATUS MESSAGE BEGAN CYCLING ON AND OFF. ALL OTHER SYS APPEARED NORMAL. CONTINUED FOR REMAINDER OF FLIGHT AND WHILE PARKED AT THE GATE ON EXTERNAL POWER. R & R ACESS BUSS SENSE RELAY K198, PN M83536/17-002L IAW ESPM 20-39-00. OPS CHECK OF EMERGENCY LIGHTS GOOD IAW AMM 33-51-00.