Help Chevy C2 !!

Greetings friends from the community. The problem I have with this vehicle is as follows. The electrventilator does not turn on. But indicate everything that is reviewed:

fully check wiring, both the branch that goes from the computer to the different engine sensors, and the one that goes from the computer to the fuse box. Media continuity and resistance (their resistance, because as the temperature bulb works by decreasing its resistance as the temperature rises. It was not going to be that due to a little common cause they will present a resistance greater than 500 OHM).

Check that the bulb decreased its resistance normally as the coolant was heated.

Check the positives (+) both of relief and food activation.

Check the electro reverse.

With multimeter and bulb tester check that the signal that the computer sends to activate the rel, which is negative or mass, was sent and this never happened. Both exciters or underwater activators remained positive (+).

For the above I think I already check everything. The vehicle does not present any other fault, it just does not turn on the electrventilator. If someone can help me I would be very grateful. Greetings.

I tell you that I am already thinking that it is a failure of ECU, but I do not know if it will be possible that only the operation of the electro -ventilator is affected.

Good night, if when the relait with a negative pulse and the motorcycle machine works, it is an indication of the absence of the negative pulse that the ECU must send, therefore there is a possible breakdown in the ECU.