Understanding FL Error in Samsung CTN364E004: Role of Fan, Mains, and Motor Sensor

Hello! The album and the problem as in the topic. FL error is fan or mains.
The fan is working, but in addition to GND and + 12V it has a third wire going to the pin described as motor sensor. I associate the engine sensor as a signal informing that the fan is working, but I'm not sure if that's the point and what the signal should be. I turned on the engine from an independent power supply, it works ok, but the sensor has no direct or alternating voltage on this pin, and this signal comes in (or out) from the control panel board.
Please let me know what should be there?

FL- DC fan motor Error, difficult topic and rarely fixable, mostly control board to be replaced.

I read a bit and I know that this is a difficult topic and read the post where the website also replaced the control board without a positive result. From the preliminary analysis of the system, I can see that the fan is controlled by two relays on the power board, 2 gradually through different power limiting resistors. It follows that this signal from the pin "motor sensor), which goes to the control board, is not a signal controlling the fan, but probably monitoring its operation. If I knew what the signal is, it would give me a lot.

As a colleague wrote above and concluded yourself that the fan works, the problem lies in the software?

Hello!
I found the damage and the board works fine. Unfortunately, it took me a long time, even though the damage was mundane. The boards are hard to repair if you do not want to replace components by feeling, only damage can be caused by measurements. This requires leading the measurement points outside the board through wires and folding the board to switch it on, especially when the damage occurs over time and under heavy load.

It turned out that one of the relays controlling the fan power was damaged. His contacts were slightly burned and he was lowering the fan power a bit. The exchange helped. I consider the topic closed.