Electrical Fan Circuit

Electrical Radiator Fan

The fan in the diagram below is controlled by a driver in the control module. When a preset engine coolant temperature is met, the PCM grounds the circuit, activating the fan motor. If the circuit is grounded before the control module, the circuit will be activated any time the ignition is switched ON.

Simple fan circuit explained.

The other choices are open circuits. A burned fuse most likely caused an open at point B. A fuse is a protection device; its fusible element melts, resulting in an open circuit when too much amperage is drawn, like the short to ground in the circuit. An open at point C stops the power flow to the motor. Without power, the motor will not function. An open at point D would remove the circuit’s necessary ground, resulting in no fan motor operation.