this cnc router worked fine yesterday. today when starting up i could not jog the machine to the homing position because the y-axis stepper motors were randomly moving in the wrong direction. i disengaged both motors/pinions from the rack and observed the same. acting erratic and randomly rotating in the wrong direction.
i am using Mach 3 with ESS. i read that the little yellow light next to the ethernet cable input should be on. it is not coming on. the green light near ethernet is blinking as it should but no yellow light. any help is greatly appreciated. Thank you, dan

It could be noise on the step and direction cables or a bad ground or are you using a pirate licence

i am using shielded cables and have never had an issue with 'noise'. all grounds and wire connections are tight at the ends, maybe a break in a wire somewhere? oh boy! lastly, i am using a legit licensed 'to me' version of mach 3. thank you for the advice. dan

Update!
after troubleshooting the issue until my eyes were bleeding, and thank you to tweakie for your help, it turned out to be bad batteries in the wireless keyboard i use out in the shop. i was told of bad keyboard batteries causing issues like typing a 'T' and getting a 'w'...so why not the 'up' arrow causing a 'down' movement, or in my case very erratic and random motor reaction.

i can say i learned alot from this and would have never thought that 2AA batteries could cause an issue like this, now i know. thank you to those that responded with ideas/help. Dan

Excellent, I am pleased that you have it sorted.

Tweakie.