In order to check the electric fan with an ECU without a car, you need:
- First you need to measure the resistance between Signal and + Ubat (K.30). It should be between 1.5 kOhm and 2.5 kOhm. If the resistance is less than 1.5 kOhm or more than 2.5 kOhm, then this indicates that the fan is defective, or its life is coming to an end, despite the fact that it can still work for some time. When measuring the resistance between Signal and + Ubat (K.30), nothing must be connected to the fan except a measuring device!
- Next, you need to apply a 12 V supply voltage from the battery or power supply to the +Ubat(K. 30) and GND (K. 31) contacts of the power connector, designed for a maximum current of at least 30 … 50 A (depending on the type of fan).
- If there is a relay on the harness, then to turn it on, connect the + Relay input to + Ubat (K.30). And for a 4-pin connector, connect the -Relay input to GND (K.31).
- For CITROEN C3, you also need to drop +12 V to the Ignition input.
- If +12 V is applied to the Signal input or nothing is connected (left in the air), then the fan should gradually spin up to maximum speed.
- If mass (GND) is applied to the Signal input, the fan should stop completely.
- To smoothly change the speed, a pulse PWM signal with a frequency of 100 Hz must be applied to the Signal input.
- In order to check the Diagnostics output, connect a 10 kOhm resistor between + Ubat (K.30) and Diagnostics, and also connect a voltmeter between GND (K.31) and Diagnostics.Then apply 12 V to the contacts of the power connector + Ubat (K.30) and GND (K.31) from a source designed for a current of 30 … 50 A. Connect Signal input to +12 V or nothing. After the fan starts to spin up, measure the voltage between GND (K.31) and Diagnostics, it can gradually increase from 0 V to 1 V at the maximum fan speed. If the measured voltage exceeds 1 V at the maximum speed of rotation this will cause an error related to the fan malfunction recorded in the engine ECU. This error may cause the fan to work incorrectly or not start at all. But with this error, the fan can be started forcibly (as described above) or using the diagnostic program on the car itself.