As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GROUND POWER IS INTERMITTENT. POWER SHUTS DOWN WHEN A LOAD IS APPLIED. FOUND BURNT "C" PHASE OUTPUT CABLE (C501-21-00C) OF GROUND SERVICE RELAY. REPLACED DAMAGED C501-21-00C CABLE BETWEEN EXTERNAL POWER CONTACTOR R2-218 AND 53-517 REF W/D 24-41-01 PG 703 SHT 2 OF 2. OPS CHECK NORMAL.