I have a 7FGCU25 in our shop because it blows the 40 amp fuse in the AM1 fuse box position.
It will blow after the engine has started and is running. Seems to require about 10 minutes of operation for this to happen.
I am surmising that there is a problem (short to ground) in the Front Harness, Toyota part # 56213-UN0RP-71.
My opinion of why it is inside the harness mentioned is because there are only 2 wires in the Front Harness large enough to require a 40 amp fuse. Those wires are a White-blue tracer that feeds the ignition switch from the 40 amp fuse, and a Black-yellow tracer that leads back to the fuse box to power all the "Ignition hot" fuse positions.
I am suspicious that the front harness has been "pinched" by something up under the dash panels, resulting in the Black-yellow wire being compressed against a ground wire inside the taped harness hard enough to cause thinning of the insulation. I think this is now bleeding through enough to cause the 40 amp fuse to heat up gradually when the ignition switch is in the Run position. If the short was between the White-blue wire it would blow the fuse just sitting turned off, but that is not the case.

Anybody ever in their life time run into this?