As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NUMBER ONE ENGINE FIRE DETECT LIGHT INOP. GROUNDED - YES. PERFORMED B737-800 FIM 26-10 TASK 805 TO RESISTANCE CHK AT F(5) OUT OF LIMITS, M1759 B/2 TO DJ2601-1 = 13.4 OHM; DJ2601-2 13.2 OHM. REPLACED MW0326 WIRE HARNESS REF B737-800 AMM 26-11-02. OPS CHECKS GOOD.