did you mean 5v?
I put the black probe on the ground of the esp32 and the red on the pin 25, i moved the red probe across the resistor to the gate of the mosfet also 3.3v.
i put the black probe on the -12v coming from the power supply and the drain 8.5v, and after the resistor it was 12v, it remained at 12v after the diode, the positive leg and the negative leg (of the terminal the heater is connected to).