What was found
DURING TAXI AFTER LANDING, FUEL FILTER BYPASS LIGHT ILLUMINATED ON NR 1 SIDE. NR 1 ENGINE OPERATING NORMALLY. GROUNDED - YES. PERFORMED B737-800 FIM 73-05 TASK 801 FAULT ISOLATION PROCEDURE, FOUND ELECTRICAL CONNECTOR FOR FUEL FILTER DIFFERENTIAL PRESS SWITCH FULLY DISCONNECTED. REINSTALLED CONNECTOR AND ACCOMPLISHED REPAIR CONFORMATION WITH NFF. BYPASS LIGHT REMAINED OUT. 8/25/2020 TSR709921: REMOVED AND REPLACED NR 1 ENGINE FUEL FILTER DIFFERENTIAL PRESSURE SWITCH, REF B737-800 AMM 73-34-01. OPS CHECK GOOD. REMOVED AND REPLACED ENGINE NR 1 J8 WIRING HARNESS, REF B737-800 AMM 73-21-06. OPS CHECK GOOD, ALL TESTS PASS.