I have a previous thread but it got a little big so here is a new problem with pictures. First picture shows our actuator. It goes into the motor controller and is supplied by the GND and 12V wire that is unplugged(circled), it is wrapped in a type of tape(forgot name) to try to defer the interference by did not help.
That is a tricky problem. As I understand it, when you connect up a 12 Volt supply to a motor controller, that affects only one pot reading on an Arduino where the pot is connected to a separate 5 Volt supply. Is that right?
What connection is there between the 12 Volt and 5 Volt supplies?
Are all grounds connected?
Where is the code that reads the pots? Did you set the analogRead input pins to be INPUT?
You have long runs of what appears to be unshielded un-twisted cables going to the pots?
Each cable to each pot would be best as shielded (shield to gnd) cables with the groung connected only at Arduino end - dont connect it to the chassis at the pot end. You should try something like microphone cable with two shielded conductors, one for 5V and one for the wiper)
You pots should not be high impedance, try 2k to 10k or so, 100k would be too high
Although I cannot rule it out, I doubt that wire shielding is the problem. Certainly, as suggested, you may want to getting a better cable. Even a USB cable would work.
You said that if you unhook up the 12 Volt supply to the motor controller, things work. If you do hook up the 12 Volt supply, things do not work. Is that even when no current is flowing to the motor controller? In other words, when the motor is not on?
The reason I ask about the pot input pins is that I think that is where the problem lies. I don't think your Arduino is reading the correct value from the steering pot. If you could confirm that by testing, that might help. You could hook your computer up to the first Arduino, have it read the pot input pins, and then have print out the values to the serial monitor.
Good to hear that solved the problem. MarkT was right. I must admit I was wrong--I never thought that would be the cause. Always good to learn something new.