TC reported Internal Smoke Pre-Alarm 2 in Rear DT car. Staff (YWT) checked and feedback no sign of s moke. ~~~~~ TC reported Internal Smoke Pre-Alarm 2 i     #3721-#1 end smoke detector air blow from smoke detector inlet hose. #3721-#2 end smoke detector and pre-alarm smoke detector air blow and clean the contact with contact cleaner.Check on Tims no re-occurance of fault.To monitor at M/L. Done by Zulqarnian/Yusof. 26/04/20