What was found
NR 1 FUEL FILTER BYPASS LIGHT ILLUMINATED FOR 15 SEC PRIOR TO TAKEOFF ROLL. LIGHT WENT OUT & STAYED OUT DURING TAXI BACK TO GATE. ACFT GROUNDED. BITE CHECK OF CDU SHOWS MESSAGE 73-31071. REMOVED, INSPECTED, & REPLACED NR 1 ENGINE FUEL FILTER IAW MM 73-11-02-000/400-801-F00. NO CONTAMINATION NOTED. REF FIM 73-31 TASK 802 FOUND CONNECTOR DP0803 LOOSE AT FUEL DIFFERENTIAL PRESSURE SWITCH. REMOVED & REPLACED SWITCH IAW MM 73-34-01-000/400-801-F0. ACCOMPLISHED REPAIR CONFIRMATION IAW FIM 73-31 TASK 802. TESTED NR 1 ENGINE IAW MM 71-00-00-800-811-F00, TABLE 502, NO FAULTS FOUND.