1685 APS Fault. To check & rectify. (DT ~~~~~ To continue rectification.  1685 OPA unit swapped to #2685. Swapped #1685 Relay board to #2686.    'AUX ON' train & APS fault illuminated. OPS 30 raised to follow-up.  Jervis 44446 1685 APS Fault.(DT Check)  1685 when "AUX ON", no APS fault indication found. Checked 1685 A/c compressor motor 'Tong' value & phase ohmic value - OK. No APS fault when A/c compressor kicked in. Performed APS check & 'POWER TEST' - OK. Meter check CCD shoe fuses to CCD shoes - OK. APS 'POWER TEST' - OK. #1685 APS fuse checked - OK. Charging resistor checked : #1685 (14.9 ohm), #2685 (15 ohm). Conductivity between DC terminals : #1685 (201 ohm)                                     #2685 (199.8 ohm) Checked all connections on cards - OK. OPS 20 raised to follow-up.  Chan SW 06/09/2021 To continue rectification.  1685 found connector CN4 wire 6789 loose. Retightened wire to connector. APS Function test - OK.  Alan/Lee PT/Shafie 44446