Possible Causes

WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

Possible causes are:

Connector or terminal malfunction
Cooling fan relay No. 4 malfunction
Open circuit in wiring between cooling fan relay No. 4 harness connector terminal "A" and PCM 30-pin harness connector terminal "4B"
Open circuit in wiring between ignition switch and cooling fan relay No. 4 harness connector terminal "E"
PCM malfunction
Short to ground in wiring between cooling fan relay No. 4 harness connector terminal "A" and PCM 30-pin harness connector terminal "4B"
Short to power circuit in wiring between cooling fan relay No. 4 harness connector terminal "A" and PCM 30-pin harness connector terminal "4B"