TC reported smoke external at rear M2 car. Staff(YCK) checked and confirmed no sign of smoke or fireon train and platform. Rear train 411 line cleared from AMK NB to YCK NB. No abnormality. ~~~~~ TC reported smoke external at 2544 car. Staff(YCK) checked and confirmed no sign of smoke or fire on train and platform. Rear train 411 line cleared from AMK NB to YCK NB. No abnormality. CE: Found Tims,showed smoke external. Reset fault cleared. No abnormality  As above mention FC721 external smoke, check and found external smoke detector sign of rusty/corrosion. Repplace new external smoke ok. Function test ok smoke detector unit S/N N.A Notif csc:2509413 Done by Haslan/Asruddin 45133