TIMS showed Fire External Alarm at RearM1 car. Staff(JUR) checked and confirmed no signs of smoke /fire / burning smell on exterior or interior of train. Rear T301 line clear and confirmed no abnormalities. ~~~~~ * ,N * Found 1537 having FC723. Found external smoke detector activated due to dust. Blowed detector with compressed air to remove dust. Function tested ok. Monitored and no fault recurrence. DONE BY: SHARIF/SYUHAIDAH 16.07.2023