PWM problem/control

Schematic_12V-Box_2021-11-12.pdf (64,6 KB)

Hi, i have got an issue with my pwm control.

I want to control a 12V water pump with a Kemo DC motor-controller which can be controlled via 0-5V PWM.
Directly after the Pump is a pressure sensor and a flow sensor.
I also have 3 PWM fans (ARTIC F 12 PWM).
Teensy 3.5 microcontroller is used.

When I'm driving the pump for example with 220 PWM and I start the Fans with any PWM Signal the pump "is driving faster" ( volume flow increases).

My code is part of a cooling system and rather long. But the failure shows up with basic programming like " analogWrite(pump,220); delay(5000); analogWrite(fan,200);"

The added wiring is working fine and the rest of my system works also but this bug is driving me crazy.
I'm new with Arduino and electronics so don't be to hard.

" teensy is at 5V Box and the cables for the two PWM Signals go to the attached plan ( green and orange)"

When things like that happen, it is usually a power issue and/or noise. Your schematic is quite difficult to follow (way too many lines running everywhere. GND and VCC can just be connected to to labels)

Anyway, Are your 12V and 5V grounds connected? it didn't look like it. You might also put in some capacitors to regulate the voltage and eliminate any noise. I didn't see any.

Its impossible to do anything but guess without information.

Circuit diagram?
links to datasheets for all the hardware components?

Does the motor speed up or does the flow sensor output change, or both?