I had the same problem. In my case the insulation on the harness has worn through between the engine and transmission and two wires had shorted against the frame. I found this by moving the harness around to clear the short with the frame. Later I repaired the harness. Not as bad a job as I thought it would be. Once I found that moving the harness allowed the engine to run, it only took about 4 hours of my amateur labor to repair the harness. No problems since.