Z Axis Wiring - Explain like I'm Five

I read the other posts on the intermittent wiring with limit switch and behavior of the Z-Axis. I had a similar issue with initializing on my second or third project. I recycled everything several times and viola, problem gone.

Today, the ghost is back. Z-Axis randomly plunged after only a few minutes running. So I hit the stop switch, recycled the power after inspecting the damage and the machine said homing fail, can’t find limit switch. Ok… so I turn everything off, move everything manually, safe my bit, check limit switches, all good. Run initialization and the Z drives full down and then signals fail. I am confused now, because other jobs have run fine. I know the wires aren’t backward.

I then start checking connections. The Z-Axis 4 pin connector has a little little tiny play in and out. Thousandths. I inspect the interior of the plug and it looks good. Plug it back in and pushed it flush. Now everything works.

My old problem may have been this weak or loose connection where one/several pins were vibrating away from good connection in the plug.

My question on the wiring of this and the logic on the board: What are the four wires? Positive, Negative, Forward/Up, Reverse/Down? What if ONE were disconnected, what behavior would be observable? What if TWO were disconnected, what would the behavior be? Meaning; the board is sending signal to go up, but that wire is loose, so the machine receives signal on the other wires and based on the construction of the motor, and lack of a balanced signal, travels the opposite direction? Is it possible a “loose” connection in the pins within the plug would cause the behavior I experienced?
Would dielectric grease in the pins assist in preventing/correcting this *if it is the problem?

Blue skies,


Stepper motors have pairs of wiring.

There’s a bit about the underlying electronics/principles at:



Image of a 3D printed motor which explains how they work:


IME, loose/intermittent connections are accompanied by horrible noises, lost steps, and burnt out stepper driver chips.

Please contact us about this at support@carbide3d.com and we’ll do our best to assist.

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