A 'diagnostic macine' is not going to help anyone track down a shorted wire.

This was the kind of work that Reeves used to throw at me all the time. All you need is a good understanding of electrical systems, a multi-meter and an electrical schematic to find and fix the problem.

Its a pain in the ass to do but good for the shop if they charge by the hour to track down the problem.

The most likely cause is that you damaged an electrical harness when working around the motor or tranny.