Cooling Fan ECU – 01MY

Cooling Fan ECU – 01MY

Fusible link 5 of the engine compartment fuse box (C0573) provides a constant battery feed to the cooling fan ECU (C0701) on an NW wire. Fuse 4 of the engine compartment fuse box (C0575) provides a feed to the cooling fan ECU (C0701) on an NK wire when the main relay is energised (see above). The cooling fan ECU (C0701) is earthed on a B wire.

To control cooling fan and condenser fan speed, the ECM (C0331) provides the cooling fan ECU (C0701) a Pulse Width Modulated (PWM) signal on a UR then NK wire. The frequency of the pulses supplied by the ECM determines the speed the cooling fan ECU will drive the cooling fan and condenser fan motors.

The cooling fan ECU interprets the PWM signal provided by the ECM as follows:

If a PWM signal of between approximately 12 % and 87 % is received by the cooling fan ECU, it will not power the cooling fans. If a PWM signal of 87 % or over is received by the cooling fan ECU, it will provide a feed to the cooling fan (C0005) and condenser fan motors (C0280) on SU wires. An earth path is provided for the cooling fan (C0005) and condenser fan motors (C0280) by the cooling fan ECU (C0701) on a pair of PS wires. If a PWM signal of less than 12 % is received by the cooling fan ECU, it assumes a fault has occurred and powers the cooling and condenser fan motors as described above. If a continuous voltage is received by the cooling fan ECU, it assumes a fault has occurred and powers the cooling and condenser fan motors as described above.