DTC P0481: Cooling Fan Relay No. 2 Control Circuit: Description

Battery voltage is supplied to the cooling fan relay and cooling fan No. 2 relay from the COOL FAN 2 Maxifuse®. The PCM controls the relays by grounding the high speed cooling fan relay control circuit via an internal solid state device called a driver. The 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 the circuit should be high (about battery voltage). If fault detection circuit senses a voltage other than what is expected, DTC will set.

PCM will monitor the control circuit for a short to ground, short to voltage or an open circuit. When PCM detects any these conditions, DTC will set and the affected driver will be disabled.