DTC P1491: Radiator Fan Control Relay Circuit: Description
Radiator fan relay voltage is monitored when ignition is on, battery voltage is more than 10 volts. DTC will set in PCM memory if PCM detects an open or shorted condition in radiator fan control relay circuit. Possible causes for DTC to set are: defective radiator fan relay, defective radiator fan, defective PCM, or defective connectors or wiring.