Locomotive Diagnostic Tool (Model LDS-04) was developed for trouble shooting and online diagnosis of the 6000 HP modern three phase locomotive fleet of Indian Railways equipped with MICAS-S2 control system of Bombardier Transportation. The equipment is built around a Pentium class processor and has a communication gateway enabling direct connection to the locomotive control system through the Multifunctional Vehicle Bus (MVB). The diagnostic tool becomes a network node on the MVB and all the vehicle processors can be accessed. The entire suite of MicTools (proprietary traction control software tools of Bombardier Transportation) can be run on this equipment to carryout many functions like control software download, fault log upload cum offline analysis, visualization and temporary forcing of process variables in real-time etc. The equipment is very compact, chassis cooled with dual input supply option of 110V DC and 230V AC 50Hz. USB interface and dual boot feature (DOS & Windows) are its unique features.