blown fuse

My 2002 ford explorer 4.0L keeps blowing fuse 41 under the hood. I want to check the pcm power diode. Can someone please tell me what it is and where it is located? I suspect the reason for my problem to be a short in 02 sensor circuit. So if I go to my pcm power diode and trace the red/yellow...

I recently put in a after market radio which recently stopped working. Its wired perfectly fine and non of the fuses are blown. Is there another fuse in the main power line to the radio that might have blown because the radio still is getting some power because it can eject disks and take them.

For some reason I keep blowing the fuse that supplies the backup lights, shift motor and O/D I think. I'm not sure why, I thought it was because of a messed up wire going to the shift motor. Today I fixed the wires on the shift motor, replaced the fuse, everything worked for a few minutes and...

if i just turn the switch on they work but if i actually start the truck the fuse blows immediatly!! is that just a wireing problem (someting shorting out) or coould that be from bad bulbs? 94 X sport