Toyota Repair: blowing the AM2 fuse in a 1990 pickup, manual tranny, pickup coil

Question
I have a 1990 toyota pickup. 4 cyl. 4wd manual tranny.  It has
185,000 mi. w/ 20,000 on the rebuilt head.  I was driving down the
road, shifted into 3rd and the power cut out.  I've been unable to
find any grounded wires, and I've replaced the ignition switch,
which had burn marks inside it, along with the ignition module and
pickup coil.  Something is still causing the AM2 fuse in the ignition
circuit to blow.  Is this a common problem with a simple solution?
Thanks,
Graham

Answer
Sorry but this is not a common problem and the solution may not be so easy. In order for this fuse to blow there must be a direct short to ground in the circuit, remove the fuse and start checking for a short to ground, start at the fuse and trace the wire until the short to ground is located, sounds simple but it's very time consuming and it helps to have a wiring diagram and being able to read it.