Both fans on the radiator turn on low when the ignition switch is moved to the II location. Troubleshooting guide says to look for a short in the wire between the terminal 4 of the relay and terminal A6 of ECM/PCM. No short.
However, there is an additional symptom: When I turn the key off after running the engine, even for just a few seconds, both fans run for 3-5 minutes on high. When I followed the circuitry through relays and diodes, it looked like the radiator fan diode (taped to a main harness above the under dash fuse box yellow/Red wire) appeared to have a burn mark on it like somehow the smoke was release from it However, it checks out fine with the meter. When I reinstalled it, the fans still do the same thing, but this time they only run on low speed.

The wiring diagram shows a diode for the A/C condenser circuit as well (Black/Yellow wire), but I cannot find that one. Any ideas where it could be located?

 

From your description the diodes are working, because the fans wouldn't work if the diode was not delivering power.

The fan control relay below the a/c compressor fan motor in your diagram sets the fans to low when it routes power through the blu/blk wire to the radiator fan motor. You may want to check if the green pin on the fan control relay is getting ground from the PCM.

Any chance the a/c button is turned on inside the car when you turn the key to the II position?

I don't think the diodes are your issue, but A/C diode A is in the engine bay fuse box. Diode B is under the dash. Look on page 21-7 if you bought the pdf of the accord shop manual from automanualsource.com.