TIMS showed Smoke External Alarm at car3512. Staff(AMK) checked and confirmed no signs of smoke ext erior or interior of train. Rear T221 line clear and confirm ed no abnormalities. ~~~~~ 3512-To Check External Smoke Detector Unit Replaced and tested ok. Not: 2479086 raise, Done by Alauddin/Sateesh/Firdaus. 11/04/23 3512 - TIMS showed Smoke External Alarm. Staff(AMK) confirmed no signs of smoke exterior or interior of train. Rear T221 line clear and confirm ed no abnormalities  3512 Smoke detector fault. Fault code 721 - smoke external fault. Removed & tagged SDR  11 Relay. Suhairi/Ahmad/Syairazi 45024 OPS 20 Raised to BSD to check exterior smoke detector unit.