1996 Jeep Cherokee Engine Shut down

I started my '96 Jeep and drove for a very short distance and the engine shut down. The starter would turn over but the engine would not start. I discovered a 20 amp fuse blown in a module control box under the hood. I replaced the fuse and the car started. After driving a short distance the engine shut down and the fuse was again blown. Looking at the guide in the top of the housing, the fuse is marked transmission and "Powertrain Control Module. The ECM module has been replaced. How do I identify the PCM and learn its location under the hood. Could this be the cause of my engine shutting down or another electrical problem. I have checked all the wiring under the hood for a frayed wire and discovered none. How can I diagnose my problem?