TIMS showed Smoke External Alarm at car3558 . Staff(AM) checked and confirmed no signs of smoke / f ire / burning smell on exterior or interior of train. Rear T 425 line clear and confirmed no abnormalities. TIMS showed S ~~~~~ 3558 - TIMS showed Smoke External Alarm. Staff(AM) confirmed no signs of smoke/fire/burning smell on exterior or interior of train. Rear T425 line clear and confirmed no abnormalities. CE checked : Checked car 3558 No smoke external alarm. No abnormality.  3558 found FC 735 on TIMS. Replaced DC-DC converter at #3558 FCP. Security check - OK. OPS 20 raised to c/o cable gland.  Irwan/Tarmidzi/Hashim 45317 BSD: 3558 Cable Gland Missing / Require CO