Cooling fan on Beta 250 EVO 2016

[Mikhail]

Hi, I have a problem with my cooling ventilator on my trials bike. It is working when the engine runs on idle, but when I open the throttle, it stops.

I was measuring the voltage and when it runs, there are 6.3V going to the fan, but as soon as I rev it, the voltage drops to 3V. I was cleaning the wiring connectors with contact spray, but all other stuff incl. ignition works just fine. Any troubleshooting tips?

Many thanks in advance.