As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKE OFF, HAD LEFT GENERATOR FAIL AND AC CROSSTIE LOCK OUT MSG. AIR RETURN TO PHX T/S LEFT GCU WITH GCU FAULT LIGHT REPLACED LEFT GCU. INSP LT GEN AND CURRENT TRANSFORMERS. ALL CKS GOOD. RAN AC CROSSTIE TEST. FAILED TEST. REPLACED LT GEN POWER RELAY. NOW CKS OK.