Is your ECM ground accidentally hooked up to +positive or the alternator shorted to ground internally? you may have said that this is the alternator from when you had a V-8 in the 'Stang?
I have had no reason to question the ecu ground. The engine harness is grounded on the chassis, in stock location...
Correct, the alternator was last used on when the car had a v8. I thought I eliminated the internal ground possibility, by disconnecting the 2 plugs on alt. Condition of burning the fuse link persisted. Also, disconnecting the main Alt cable had no effect.
I spent a week thinking I had a failure in my alarm system; AvantGard 4, from Clifford. Originally installed (certified shop), around 1999. I have been able to bypass the ignition circuit out of the alarm system, and the fusible link still burns.
The best clue I have at this point seems to be that little gray connector shown above, between the engine harness and the chassis harness.
Ignition wire does pass through this plug.
However, when I disconnect the plug, and only jumper the ignition wire, fusible link does not burn.
Plan for this afternoon/evening, is to build multiple jumper wires for this connector, so that I can test which wire is shorting to ignition.
Obviously I had to cancel the appointment for alignment...