Fan won’t work, fuses are all fine and there’s power going to the fan, fan still works fine when plugged into battery, must be a problem with the earth from the fan ??
Electrics, ECU, Warnings & Lights
though relays often controlled via ECU.
Try a jumper ground to the fan motor.
Or try a 12 V test bulb connected to battery pos+ and other end to the fan ground plug pin.