As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON PREFLIGHT, NR 1 ENGINE A LOOP FAULT. NO FAULT NOTED ON B LOOP. GROUNDED-YES. ACCOMPLISHED TSR710174, REPLACED ENGINE NR 1 MW0315 AND MW0325 HARNESS, REF B737-900 AMM 26-11-02-400-801 AND REF AMM 26-11-02-400-802. OPERATIONS NORMAL, REF AMM 26-11-00-710-801.