I have tested the pressure and temperature switches, and they are good.
The fan operates with 12v directly applied.
I have tried four different relays in each of the two-silver ice cube shaped relays located on the driver's side fender under the black box.

The only thing that I think it could be now is the wiring from the relay to the auxiliary fan plastic wire connector.

Maybe there is a pinched wire or a section that is broken.

Anyone else ever have this issue?