Front DT car train doors not proven closed with DIR lit after train switched to north cab 3517 at MS P siding. TC confirmed all train doors physically closed at Front DT car and opened/closed both side cab doors but to no ~~~~~ Front DT car 3517 train doors not proven closed with DIR lit after train switched to north cab 3517 at MSP siding. TC confirmed all train doors physically closed at Front DT car and opened/closed both side cab doors but to no avail. DIRBS was operated.  [FYI] Fault able to be duplicated in depot. In depot, Found #3517 B2 ECB lighted and DIR triggered, TIMS did not receive ECB command. Found ECB button switch NO contact 9447D/9401 NG (fluctuating 8-20ohms) causing DIR to trigger. TC did not receive ECB alarm at cab as ECB switch contact and TIMS switch contact (TN24/T196) were not triggered. TC DIRBS to move train. --> DIR triggered due to ECB Relay sharing same loop as DIR loop. Further checked saloon door were proven closed. Both cab doors were proven closed. - Checked 3517 B2 ECB contact no signs of loose wiring or water ingress - Replaced new ECB contact switch for 3517 B2 ECB and function tested satis. - 3517 DIRBS resealed. Done by: Kenneth/Zulq 13.6.24