DTC P0480: Cooling Fan No. 1 Relay Control Circuit: Notes

Battery voltage is supplied to cooling fan No. 1 relay from fuse No. 6 (COOL FAN 1 maxi-fuse). The Powertrain Control Module (PCM) controls cooling fan 1 relay by grounding the low speed cooling fan relay control circuit via an internal solid state device called a driver. Primary function of the driver is to supply ground for the component being controlled. Each driver has a fault line which is monitored by PCM. When PCM is commanding a component on, voltage potential of control circuit should be low (about zero volts). When PCM is commanding that the control circuit to a component be turned off, voltage potential of circuit should be high (about battery voltage). If fault detection circuit senses a voltage other than what is expected, Diagnostic Trouble Code (DTC) will set.

PCM will monitor the control circuit for short to ground, short to voltage, open circuit, open relay coil, internally shorted or excessively low resistance relay coil. When PCM detects any of these conditions, DTC will set and the affected driver will be disabled.